Lessons From Bischofsgrün: Don't Help A Bad Bishop

IN round six I essayed a move that is audacious and unusual, but apparently perfectly sound.

White has just played 17.Rc1-c2 in Patrick Chochoy (1757) - Spanton (1954)

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I replied 17...Bxc3!?, which occurs in just seven of 121 games in ChessBase's 2025 Mega database.

The point is that after the further moves 18.Qxc3 Qxc3 19.Rxc3, Black has exchanged queens (usually a good idea in the Maróczy Bind), so dark-square weaknesses around the black king are unlikely to be exploitable. And as I pointed out in my notes to the game, 18.Rxc3 Na4 also forces queens off.

Position in the game after 19.Rxc3

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However, I spoilt the concept by continuing 19...f5?, allowing White to open lines for the bishop-pair, and in particular letting White move the e4 pawn (either by capturing on f5 or, even better, advancing to e5), which helps make White's light-square bishop less bad.

LESSON: opening lines is rarely a good idea when the opponent has the bishop-pair and you do not, exceptions normally only occurring when there is a concrete short-term reason.

Bischofsgrün Round Six

FACED a Frenchman.

Patrick Chochoy (1757) - Spanton (1954)

Maróczy Bind

1.e4 c5 2.Nf3 Nc6 3.d4 cxd4 4.Nxd4 g6 5.c4

Entering the Maróczy Bind scores a very healthy 57% in ChessBase's 2025 Mega database, while the more popular 5.Nc3 returns a disappointing 49%.

5...Bg7 6.Be3 Nf6 7.Nc3 d6 8.Be2 0-0 9.0-0

This position occurs 19,854 times in Mega25

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9...Bd7 10.Qd2

The one time Géza Maróczy had the position after 9...Bd7, in a 1906 game, he played 10.h3, which had been played against him two years previously in the stem game. That also seems to be Dragon1's top choice, very marginally ahead of the unusual 10.Re1!?, although the engine does for a while prefer the text. Stockfish17 likes the trendy 10.Nc2!?, again ahead of 10.Re1!? 

10...Nxd4

This is why 10.Nc2!? has become fashionable - to prevent Black reducing the cramp in the black position by initiating exchanges.

11.Bxd4 Bc6 12.f3 a5!?

The main point of this move is to secure c5 for the remaining black knight. It also gains space, but more-or-less gives up hopes Black might have of breaking the Bind, or at least challenging it, with ...b5.

13.b3 Nd7

We are still very much in mainstream theory - this position occurs 2,404 times in Mega25

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14.Be3!?

This is easily the commonest continuation, following the advice that when you have a bad bishop (White's light-square bishop is hemmed in by its own pawns) avoid exchanging your good one.

14...Nc5 15.Rab1

Again easily the main continuation.

15...Qb6!?

Self-pinning looks strange, at least at first sight, but White cannot immediately take advantage of Black's setup on the g1-a7 diagonal.

16.Rfc1

This position occurs 1,114 times in Mega25

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16...Qb4!?

The engines prefer this over the much more common 16...Rfc8.

17.Rc2

This is the usual response, but the engines suggest 17.Qb2!?

17...Bxc3!?

This unusual continuation - normal is 17...Rfc8 - is the top choice of the engines.

How should White recapture?

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18.Qxc3

This lets Black follow through with the main idea of 17...Bxc3!? - getting queens off the board.

Instead, after 18.Rxc3!? it appears at first that Black can take on e4 with the bishop as 19.fxe4?? loses to 19...Nxe4, followed by snaffling the c3 rook. But White does not have to fall in with Black's plans, and can play 19.Rb2!? Bc6 20.a3!, meeting both 20...Qxa3 and 20...Qb6 with 21.b4, winning material. The engines also point out 19.a3!?, which also seems very good.

However Black does not have to play 18...Bxe4? - rather 18...Na4 forces an exchange of queens, as in the game.

18...Qxc3 19.Rxc3

How would you assess this queenless middlegame?

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White has more space and the bishop-pair, although the latter factor is tempered by there being 14 pawns on the board, with all but one white pawn on the same-colour squares as White's light-square bishop. The Black knight is well-posted, for now - it faces being evicted by White playing a3 and b4. Dragon1 gives White a slight edge, but Stockfish17 calls the game equal.

19...f5?

This novelty is misdirected. Better are the known moves 19...Ne6 and 19...b6, but two other known moves - 19...Rfc8? and 19...Rfb8? - are mistakes because of the reply 20.e5.

20.exf5?!

This is good enough for an advantage, but 20.e5 is stronger, eg 20...f4 (20...dxe5?? 21.Bxc5) 21.Bf2 Rfe8 22.exd6 exd6 23.Bf1, when the isolated d pawn is a serious weakness.

20...Rxf5 21.Bxc5?!

White should almost certainly not give up the better white bishop.

21...Rxc5

The engines slightly prefer 21...dxc5!?

22.Re3 Kf7 23.f4 b6 24.Re1 e5

The engines prefer passive-looking defence with 24...Re8 or 24...Ra7.

25.fxe5

The engines give White a slight edge (Dragon1) or the better part of equality (Stockfish17) after 25.Rf1.

25...dxe5

The pawn is isolated, but passed. However the engines prefer 25...Rxe5!?

26.a3 e4 27.Bd1 Re5 28.Bc2 Rae8 29.Rd1 Kf6 30.g3!? g5 31.g4 Kg7!? 32.Rd6 R5e6 33.Rd1 Rf8

How should White proceed?

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34.Rde1?!

The engines strongly dislike this, reckoning 34.b4 maintains equality (Stockfish17 is also fine with 34.h3, but Dragon1 reckons it leaves Black with a slight edge).

34...Rf4 35.h3

This looks natural, but the engines prefer 35.Bd1.

35...Kg6

The engines give 35...Kf6!? as much stronger, eg 36.Bd1 Ke5 37.Be2 Kd4 38.Bf1 a4, when suddenly White's queenside is vulnerable.

Going back to the last diagram, after the suggested 34.b4 there might come 34...axb4 35.axb4 Rf4, but 36.h3 is now fine, presumably because there is little chance of the black king attacking White's queenside.

This is really quite subtle stuff, and I do not suppose even a small fraction of it crossed either player's mind.

36.R1e2?!

The engines much prefer 36.b4 or 36.Rd1.

36...h5

They again like ...Kf6, and if 37.Rd2, then 37...Ke5, with ...Rd6 to come so the black king can gain access to the queenside.

37.gxh5+ Kxh5 38.Rg2?!

The engines suggest 38.Rd2, or 38.Bd1 followed by Rd2.

38...Rf3?

The engines reckon taking the open d file with 38...Rd6 is strong.

39.Bd1 Rd6 40.Bxf3+ Kxf3 41.Rf2

Possibly better is 41.Rg3, hoping to give back the exchange in return for the f pawn. However 41...Rd1+ 42.Kf2 Rd2+ 43.Kf1 a4!? (43...Rd1+? 44.Re1 Rd3 45.Re5) 44.bxa4 Ra2 seems to give enough counterplay.

41...g4 42.hxg4+ Kxg4

Now the f pawn is fully protected, and the position is completely equal, according to the engines, but tricky

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43.Re7 Rg6?

This lets White threaten to activate his king. Instead both 43...Kf4 and 43...Kg3 keep a lid on the position, while also holding are moves such as 43...Bd7 and 43...Rd1+ (meeting 44.Re1 with 44...Rd2).

White to play and (probably) win

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44.Kh2

After 44.Rh2! the only way to stop White's king getting active with 45.Kf2 is 44...Kg3, but the engines reckon 45.Reh7! wins, eg 45...Rd6 46.R2h3+ Kf4 47.R3h6!  Rd1+ 48.Kf2 Rd2+ 49.Ke1 Re2+ 50.Kf1 Be4 51.Re7 Re3 52.Rh4+ Kf5 53.Rf7+ Ke6 54.Rf8 Ke7 55.Rb8 etc.

This is a difficult line to foresee, and White has to find a lot of good moves, eg 47.R7h6, instead of 47.R3h6!, does not win, eg 47... Rd1+ 48.Kf2 Rd2+ 49.Ke1 Re2+ 50.Kf1 Be4 reaches a similar position, but 51.Re6, instead of 51.Re7, can be met by 51...Bf5 52.Rf6 Rb2, with sufficient counterplay, while the alternative 51.Rxb6, which at first might be thought an improvement, can be met by, among other moves, 51...Ke3, eg 52.Rd6 (52.c5? Rc2 53.Kg1 Bf5 54.Rg3 Rc1+ 55.Kh2 Kf4 wins for Black) Rf2+ 53.Kg1 Rg2+ 54.Kf1 (not 54.Kh1?? Rg4 with ...Ke2 and f2 etc to come) Rf2+ etc.

44...Rh6+ 45.Kg1 Rg6?

Giving Black another chance to play Rh2.

46.Kh2 Rh6+ ½–½

Munich 60+ Round Seven

RECEIVED a double-upfloat against an Indian born in 1973 (the tournament is supposedly for players born before 1966, but having a 'junior' means there is an even number of players, and he is not eligible for a prize).

Kumar Suresh (2100) - Spanton (1954)

Maróczy Bind

1.e4 c5 2.Nf3 g6 3.d4 cxd4 4.Nxd4 Nc6 5.c4 Géza Maróczy

One of the main points of Black's Accelerated Dragon move-order is to try to get in the move ...d5 without, as in normal Dragons, spending a tempo on ...d6. The text, which prevents that, is the top choice of Stockfish17 and Dragon1, and scores 57% in ChessBase's 2025 Mega database, eight percentage points more than the commonest continuation 5.Nc3.

5...Bg7 6.Be3 Nf6 7.Nc3 d6 8.Be2 0-0 9.0-0 Bd7

This position seems to have first been reached in Rudolf Swiderski - Géza Maróczy, Monte Carlo 1904 

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Maróczy won that game, but was impressed enough by White's structure to write in praise of it, although, according to Wikipedia, he never played the Bind as White (a cursory search of Mega25 alone shows this to be untrue - he used it just two years after Monte Carlo to beat the German-American master Hermann Voigt).

10.Rc1

Swiderski - Maróczy went 10.h3 Nxd4 11.Bxd4 Bc6 12.Qd3 Nd7!? 13.Bxg7 Kxg7 14.b4!? b6, with the upper hand for White, according to the engines (but 0-1, 48 moves).

The text is second in popularity in Mega25 to 10.Qd2.

10...Nxd4 11.Bxd4 Bc6 12.f3 a5!?

This gives up the b5 square, in that a white piece can no longer be prevented from landing on it, but of more importance, Black hopes, is securing of the c5 square for the black king's knight.

13.b3 Nd7!?

Mega25 has 346 examples of this position - how should White proceed?

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14.Kh1

According to Russian-Dutch grandmaster Sergei Tiviakov, an exchange of dark-square bishops nearly always favours Black in the Maróczy Bind, despite weakening the position of black's king. The commonest move in Mega25 is 14.Be3, but 14.Bxg7 has been played by grandmasters, and is easily the second-most popular move.

14...Bxd4 15.Qxd4 Qb6!? 16.Qxb6!?

White's extra space, and the dark-square weaknesses around Black's king, might make avoiding a trade of queens seem attractive, but after 16.Qd2 the engines reckon 16...a4 is good for Black.

On making his move, KS pressed the clock and offered a draw.

How would you assess the position?

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After ...

16...Nxb6
... Black's knight has been diverted from the c5 outpost, but with queens gone the weaknesses around Black's king are largely irrelevant, and Black has the better bishop, albeit one that does not have much scope on a board crowded with pawns. However, White still has a space advantage - Black does not seem near to breaking the Bind - and the engines reckon White has the better part of equality.

17.Nd5!? Bxd5 18.cxd5 Rfc8

The trade on d5 has left Black with a good knight against a bad bishop, but the bishop has a little more freedom than it had previously, and a bishop often cooperates with rooks better than a knight manages

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19.Kg1 Rxc1!?

Bearing in mind the last note, it might seem desirable to force rooks off, but this case may be an exception as in the resulting position White's king will be more active, and White will find it relatively easy to get white pawns off light squares, freeing the bishop and gaining space.

20.Rxc1 Rc8 21.Rxc8+ Nxc8 22.Kf2 g5!?

This is Stockfish17's top choice; Dragon1 prefers pushing the e pawn (one square or two).

23.Ke3 Kg7 24.g3 e5?!

This encourages an opening of the position, favouring the bishop.

25.dxe6 fxe6 26.f4

Even stronger, according to the engines, is 26.Kd4 (as will become apparent).

26...gxf4+ 27.gxf4 Kf6?!

Allowing White to reach a position that could have arisen after 26.Kd4. Instead 27...e5!? equalises (Stockfish17) or leaves White with only a slight edge (Dragon1), one point being 28.f5 can be met by 28...d5!? 29.exd5 Nd6.

28.Kd4 b6 29.Kc4 Na7 30.a3 Nc6 ½–½

Naturally not 31.Kb6?? Nd4+ etc, but the engines reckon White is winning, one line running 31.a4 Na7 32.Bg4 h6 33.h3!? Ke7 34.f5 exf5 35.exf5 Nc6 36.Kb5 Nd4+ 37.Kxb5 Nxb3 38.Bd1 Nd4 39.Kxa5 Nxf5 40.Kb6, after which Black seems helpless to stop White's passed pawn.

Bodensee Senioren Round Five

FACED my first Austrian.

Spanton (1937) - Josef Granabetter (1840)

Maróczy Bind

1.e4 c5 2.Nf3 e6 3.d4 cxd4 4.Nxd4 a6 5.c4 Nf6 6.Nc3 Qc7 7.Be3

The commonest move in ChessBase's 2025 Mega database is 7.a3!?

7...d6 8.Be2 Nbd7 9.0-0 b6 10.Rc1 Bb7

Black has set up a Hedgehog that will be completed by ...Be7 and ...0-0

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According to Wikipedia: "Although Black's position is cramped, it has great latent energy, which may be released if Black is able to play ...b5 or ...d5 at some point. These pawn breaks are particularly effective because White usually places pawns on c4 and e4 (the Maróczy Bind)."

11.f3 Rc8 12.b3 Qb8 13.Qd2 Be7 14.Rfd1 0-0

Now both sides have castled, how would you assess the position, which occurs 152 times in Mega25?

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White's extra space gives a slight edge, according to Stockfish17 and Dragon1.

Can you guess White's most popular continuation?

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15.Nc2!?

The main line in Mega25 runs 15.Bf1!? Bd8!? 16.Qf2 Bc7 17.g3!? Rfe8 18.Bg2, when Dragon1 gives White a slight edge, but Stockfish17 reckons Black has equalised. If you correctly guessed White's move, and especially if you expected Black's reply, you are either familiar with the theory or should seriously consider taking up the Hedgehog.

The text, which is second-most popular in Mega25, unveils pressure against d6 and b6.

15...Qa8!?

Normal is 15...Bd8!? (16.Qxd6?! Bc7) or 15...Rfe8.

16.Na4 d5?

Thematic, but the loss of a pawn is too much. The engines give 16...Qb8, the idea being to meet 17.Nxb6 with 17...Nxb6 18.Bxb6 Bxe4.

17.exd5

Even stronger, according to the engines, is 17.cxd5, eg 17...exd5 18.e5 Ne8 19.f4 b5 20.Bg4!?

17...exd5 18.Nxb6

Not 18.Bxb6?? Nxb6 19.Nxb6 Bc5+ etc.

18...Nxb6 19.Bxb6 dxc4 20.Bxc4 Bc5+ 21.Bxc5 Rxc5 22.Ne1 Rh5

Black has pressure against the weakened white kingside, but not enough for a pawn, according to the engines

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23.Qf4 Qa7+ 24.Kh1 Nd5 25.Bxd5 Rxd5 26.Rxd5 Qxd5 27.Nd3 a5

The engines suggest 27...h6 or 27...Rd8. albeit giving White the upper hand.
28.h3 h6 29.Qe5 Qa8 30.Nf4

How should Black proceed?

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30...Bc6??

Black has to go in for 30...Bxf3!? 31.gxf3 Qxf3+, when 32.Kh2 Qf2+ 33.Ng2 Qxa2 leaves White up a knight for two pawns, but with only a slight edge (Stockfish17) or at most the upper hand (Dragon1).
Also losing is 30...Bb7?? 31.Rc7 (31.Nh5 is also strong), eg 31...Re8 32.Qf5 Rf8 33.Ng6 etc.

31.Nh5 1-0

4NCL Final Weekend: Game One

PLAYED on board two (of six) for Wessex B against Ashfield 3 in division four of the Four Nations Chess League this afternoon.

Spanton (1976 ECF/1937 Fide) - Alex Bentley (1763 ECF/1784 Fide)

Sicilian ...e6/Maróczy Bind

1.e4 c5 2.Nf3 e6 3.c4 Nc6 4.d4 cxd4 5.Nxd4 Nxd4!?

This makes an odd impression, at least to me, but it has been played by Vladimir Epishin (2667), Bogdan Lalić (2507) and other grandmasters.

6.Qxd4 d6

The main line in ChessBase's 2025 Mega database runs 6...Ne7 7.Nc3 Nc6 8.Qd1 Bc5, with an equal position, according to Stockfish17, although Dragon1 favours White.

7.Nc3 Nf6

If 7...Ne7, then 8.Be3, when 8...Nc6 can be met by 9.Qd2 with a more harmonious development than in the previous note.

8.Be2 Be7 9.0-0 0-0

Now both sides have castled, how would you assess the position?

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White has achieved a Maróczy Bind, while also being slightly ahead on development. The engines reckon White has the upper hand.

10.Rd1!?

Of the 29 games to reach the position in Mega25, 10.Be3 was played in 21 of them, but the engines prefer the text.

10....Qd7

This seems to be a novelty. Known moves are 10...e5 and 10..a6, while the engines suggest 10...Bd7 or 10...b6.

11.Bg5 Rd8?!

Probably better is 11...h6!?, when the engines reckon 12.Bxf6 Bxf6!? 13.Qxd6 Qxd6 14.Rxd6 g5!? leaves Black with enough compensation for a pawn (Stockfish17), or at least only slightly worse (Dragon1).

12.Rd3

Even stronger, according to the engines, is 12.e5!?

12...Ne8 13.Bxe7 Qxe7 14.e5 Bd7?

Better is 14...b6.

15.exd6 Qf8!? 16.Bf3 Bc6 17.Bxc6?!

The engines prefer 17.c5.

17...Rxd6!

This is much better than 17...bxc6 18.c5.

18.Bd5 exd5 19.cxd5?

The knight recapture is significantly stronger.

19...Nf6 20.Rad1 Qe7 21.Qc4 Rad8

How would you assess this pawn-up middlegame?

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White is obviously better - winning, according to the engines - but the extra pawn is firmly blockaded, and, as will be shown, making progress proves difficult.

22.h3

If 22.Nb5 Black has 22...Rxd5! 23.Rxd5 Nxd5, when 24.Rxd5?? loses to 24...Qe1+ 25.Qf1 Qxf1+ 26.Kxf1 Rxd5. White instead remains a pawn up after 24.Nxa7, but no longer has a passer, and is no longer winning, according to the engines.

22...a6 23.a4 h6 24.b4 Qd7 25.b5

The engines suggest 25.Rd4, one line running 25...Re8 26.Qd3 Kf8!? 27.Kf1!? Qc7 28.Rc4 Qd7 29.Rd4 Qc7 30.Qf3 Re5, but it is unclear how White makes progress.

25...a5 26.Ne4 Nxe4 27.Qxe4 Re8 28.Qd4 b6

The engines prefer 28...Rd8.

29.Rg3 f6 30.Rdg3 Re5 31.Qc4 Qf5

Active, but not liked by the engines, which suggest holding tight with, for example, 31...Kh7.

32.g4?!

Probably stronger is 32.Re3, when 32...Rxe3 33.fxe3 will allow the d pawn to be supported by a fellow pawn, while 32...Qh5 33.Qc8+ Kh7 34.g4!? Qg5 35.Rxe5 Qxe5 36.Qf5+!? gives White a winning rook-and-pawn ending, according to the engines. In the latter line, if Black instead plays 35...fxe5, then 36.Qc4 consolidates, after which there is much less pressure on d5, and both sides have an isolani, but White's is the only passed one, and White remains a pawn up.

32...Qd7 33.f4?!

The engines much prefer 33.Re3, one point being 33...Rexd5?? loses to 34.Red3.

33...Re8 34.Qd4 f5!

White's king is much less safe than Black's - a key factor in heavy-piece middlegames

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35.gxf5 Qxf5 36.Rg3 Rg6

How should White proceed?

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37.Qf2?

Both 37.Qd3 (37...Re1+ 38.Kg2) and 37.Rxg6 Qxg6 38.Kf2 keep the position equal.

Black to play and win

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37...Rd6

AB offered a draw.

Instead 37...Re2! wins as 38.Qf3 can be met by 38...Qxh3!

Should I have accepted the draw offer?

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Black has full compensation for a pawn, according to the engines, and the Black position is easier to play, thanks to White's three isolated pawns and exposed king, so objectively, ratings aside, it is hard to make out a case for playing on.

38.Qg2 Re7 39.Qf3 Red7 40.Qe3 Rxd5 41.Rxd5 Qxd5 42.Qxb6?

White has nothing better than taking a draw by perpetual.

Black to play and win

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42...Qd1+

The engines show that the clever move 42...Qe4! wins as Black has no good answer to 43...Rd1+.
43.Kh2 Qd2+ 44.Kh1

Not 44.Rg2?? Qxf4+ etc.

44...Qd5+ 45.Rg2 Re7 46.Qc6

Not 46.Qxh6?? Qxg2+ etc.

46...Qd1+ 47.Kh2 Qxa4 48.Qd5+ Kh7 49.Qf5+ Kg8 50.b6 Qb4 51.Rc2

Black to play and draw

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51...Qe1??

Black had to guard the back rank with 51...Re8, and if 52.Rc8 White cannot escape perpetual check after, for example, 52...Qd2+ (exchanging rooks also draws).

52.Rc8 Re8 53.Rxe8+ Qxe8

White to play and win

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54.Qe5?

The simplest win is 54.Qd5+ Kh8 55.b7, meeting 55...Qe2+ with 56.Kg3, after which the checks eventually run out, but not 56.Qg2? as 56...Qb5, followed by pushing the a pawn, draws.

Black to play and draw

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54...Qf7?

The engines reckon 54...Qc6 definitely draws, eg 55.Qxa5 Qc2+ 56.Kg3 Qd3+, when the white king cannot escape the checks, and 54...Qd7!? may draw, although Dragon1 is a lot less convinced than Stockfish17.

55.Qc7 Qa2+ 56.Kg3 Qb3+

White to play and win

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57.Kh4

The engines show only 57.Kf2! wins - not an easy move to find.

Black to play and draw

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57...g5+?

The engines show both 57...Qf3 and 57...Qe3!? draw as the white king cannot escape perpetual check.

58.fxg5 hxg5+ 59.Kxg5

The white king has no cover on the kingside, but it does not need it as the black queen has no support and cannot stop the white king reaching cover on the queenside

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59...Qd5+ 60.Kf6 Qf3+ 61.Ke7 Qf7+ 62.Kd8 Qf8+ 63.Kd7 Qf7+ 64.Kc8 Qe6+ 65.Kb8 1-0

Wessex B won the match 4-2.

Fareham Round Four

TOOK a halfpoint bye in round three.

David Collyer (1968) - Spanton (1984)

Sicilian Maróczy Bind

1.e4 c5 2.Nf3 g6 3.c4!?

Ensuring White will get a Maróczy Bind.

3...Nc6 4.d4 cxd4 5.Nxd4 Bg7 6.Be3 Nf6 7.Nc3 d6 8.Be2 0-0 9.0-0

How would you assess this position. which occurs 19,854 times in ChessBaase's 2025 Mega database?

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White's space advantage gives a slight edge, according to Stockfish17 and Dargon1.

9...Bd7 10.f3!?

This has been played by many strong players, including Capablanca, Alekhine, Kramnik and Short, but more popular are 10.Rc1 and especially 10.Qd2.

How should Black respond?

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10...Qb6!?

The engines prefer the main continuation, 10...Nxd4, meeting 11.Bxd4 by offering an exchange of dark-square bishops with 11...Nh5!? (Dragon1 also likes 11...a6). After 12.Bxg7 Nxg7 White is left with a bad bishop, and will not find it easy to exploit the weakening of the black king's position. Nevertheless the engines give White an edge.

How should White meet Black's queen development?

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11.Na4

This is the most popular continuation in Mega25, but the engines slightly prefer 11.Kh1!?, when 11...Qxb2!? allows the queen to be trapped after 12.Na4, eg 12...Qb4? 13.Bd2 Qa3? 14.Nb5, or 12...Qa3?! 13.Bc1, when 13...Qb4 14.Bd2 transposes to the previous line. The engines suggest 12...Qxa1!? 13.Qxa1 Nxd4 14.Bxd4 Bxa4, when Black has rook, knight and pawn for the queen, but the engines give White the upper hand.

Far from clear is 11.Qd2!? Nxe4!?, although after the fireworks of 12.Nxc6 Nxd2 13.Nxe7+ Kh8 14.Bxb6 Nxf1 15.Bf2 Bxc3 16.bxc3 Rae8 (16...Rfe8?? 17.Bd4+ f6 18.Bxf6#) 17.Bd4+ f6 18.Nd5 Rxe2 19.Nxf6 Rxf6 20.Bxf6+ Kg8 21.Kxf1, the resulting position is completely equal (but there were many chances to go wrong along the way).

11...Qa5 12.Nxc6

The engines prefer 12.Nb5 or 12.Nc3, claiming a slight edge for White.

12...bxc6 13.c5!?

This had been seen in Ninh Ngo (no Fide) - Minh Hoang Pham (2479), Hanoi 1995, which continued 13...Rfd8 14.Bd2 Qc7 15.Bf4 Be6 16.Qc2, with an equal game, according to the engines (but 0-1, 59 moves).

13...d5!?

The engines reckon this is an improvement on that game.

14.e5 Ne8 15.f4 Rb8 16.b3 f6 17.Bd4?!

The engines give 17.Bg4!? Bxg4 18.Qxg4 Nc7 19.f5 with attacking chances, although they prefer Black.

17...Qc7?!

The engines reckon 17...fxe5 18.fxe5 Rxf1+ 19.Qxf1 Qd2 is very good for Black.

18.Bg4?

Too late! Instead 18.exf6 Bxf6 19.Qd2 leaves White only slightly worse, according to the engines.

18...fxe5 19.fxe5?!

Probably better is 19.Bxd7 Qxd7 20.Bxe5.

19...Rxf1+ 20.Kxf1 Rb4!?

The engines agree this is best.

21.Rc1 Qc8

Even stronger seems to be 21...Bxe5!? 22.Bxe5 Qxe5, although the engines are not sure how to meet 23.Bxd7. One line runs 23...Nf6 24.Qd2!? Rf4+ 25.Kg1 Nxd7, after which Black is a pawn up, has the better coordinated pieces and a pair of passed pawns. Trying to hold on to the extra piece with, for example, 24.Bh3 runs into 24...Rf4+ 25.Kg1 Qe3+ 26.Kh1 Ne4.

22.Bf3 Bh6!? 23.Rc3 Ng7 24.a3 Rb8

Sacing the exchange with 24...Rxd4!? 25.Qxd4 Nf5 is also tempting, but the engines disagree as to whether it is better than the text.

25.Nb2?

The engines suggest making the king safer with 25.Kg1, or opposing Black's dark-square bishop with 25.Be3, or advancing on the queenside with 25.b4.

25...Qa6+ 26.Nd3 Nf5 27.Bf2

How should Black proceed?

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27...d4?!

Simply taking the a3 pawn is good, but the engines also like 27...Ne3+ 28.Bxe3 Bxe3.

28.Rc4 Ne3+ 29.Bxe3 Bxe3 30.Ra4 Qb7 31.Rb4 Qc7 32.Rxb8+ Qxb8

Black has the bishop-pair and is slightly better, according to the engines, but White has queenside play

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33.b4 Qf8 34.Ke2

The engines suggest first playing 34.Qb3+, meeting 34...Kg7 with 35.Ke2.

34...Qf7 35.Qc2 g5?!

Black should slow White's queenside play with 35...a6, according to the engines.

36.a4?!

This may be too slow. Instead 36.b5! cxb5 37.c6 gives complete equality, according to the engines.

36...a6?!

The engines like 36...g4 37.Be4 Qh5, and if 38.b5 then 38...Bf5!?

37.b5 axb5 38.a5?

White has complete equality after 38.axb5, according to the engines.

38...g4 39.Be4 Be6?!

Best may be 39...Bc8!?, and if 40.Bxc6 then 40...b4, eg 41.Be4 Ba6 42.Ke1 (Black's threats included 42...Qf2+) b3 43.Qb2 Qc4 etc. Instead White should probably play the immediate 40.Ke1, although Black seems to remain on top in a sharp position.

40.a6 Bb3 41.Qb1?!

The engines reckon 41.Qb2 maintains equal chances.

41...Bc4

White to play and lose

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42.a7??
This allows mate in two.

White had to play 42.Ke1, when the engines agree the best reply is 42...e6, but their evaluation of the position fluctuates wildly, albeit coming to give Black the upper hand.

42...Qf2+ 0-1