Colle-Zukertort
1.Nf3 d5 2.d4 c5!? 3.e3
This narrowly edges out 3.c4 for popularity in ChessBase's 2026 Mega database, but the latter move is preferred by Stockfish17.1 and Dragon1.
3...Nf6 4.b3 e6 5.Bb2 cxd4!?
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| How should White recapture? |
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6.exd4!?
This is the top choice of the engines, even though the move blocks the long dark-square diagonal. The point is that the white queen's bishop will play an important role in supporting the king's knight, which at some point is likely to land on e5.
6...b6!?
A rare continuation.
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| How should White respond? |
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7.Bd3
Yahli Sokolovsky (2369) - José Eduardo Martínez Alcántara (2591), Chess.com Blitz 2022, continued 7.Bb5+ Bd7 8.Bd3, with a slight edge for White, according to the engines (but 0-1, 55 moves).
7...Bb7 8.Nbd2 Nc6!?
This interferes with the light-square bishop's action on the long light diagonal, but means White will probably be obliged to spend a tempo on preventing ...Nb4.
9.a3
This is not immediately necessary, eg 9.Ne5!? prevents 9...Nb4?? as the latter loses to 10.Bb5+ Ke7 11.Ba3, with c3 to come.
9...Bd6
Carlsen played 9...g6!? in a rapid game, but the engines are unimpressed.
10.Ne5 Qc7 11.f4
The engines agree this is better than 11.Ndf3, but they also like 11.Qe2!?
11...Ne7!?
The engines suggest an apparent-novelty in 11...Ne4!?, the point being 12.Nxe4 dxe4 13.Bxe4 can be met by 13...Nxe5, when 14.Bxb7 Qxb7 15.fxe5 Qxg2 16.Rf1 Rc8!? seems roughly equal.
12.Rc1 0-0 13.0-0
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| Now both sides have castled, how would you assess the position? |
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White has a well-placed knight at e5, and more space on the central-kingside, but Black has no weaknesses, and enjoys some pressure against the white queenside. Equal chances, according to the engines.
13...Rac8 14.Qe2 Ng6 15.c4
The engines suggest another apparent-novelty, this time 15.c3!?, a possible continuation being 15...a6!? 16.a4 Ne7!? 17.Bb1!? (17.Bxa6 Bxa6 18.Qxa6 Nf5 gives Black reasonable compensation for a pawn, according to the engines) Ng6!? 18.Bd3!? Ne7!? 19.Rf3, with a roughly equal position, but there is a lot about these moves I do not understand.
Popular in Mega26 is 15.g4, when the engines suggest 15...b5!?, the point being 16.Bxb5 can be met by 16...Ne4, eg 17.Qe3 Nh4 18.Be2 f5, with what they reckon is more than enough for a pawn. And if White instead continues on the kingside with 16.g5, then 16...Ne4 17.Nxe4 dxe4 18.Bxe4 Bxe4 19.Qxe4 f5!?, and again Black has good compensation for a pawn, according to the engines.
15...Qe7 16.b4 dxc4 17.Ndxc4 Bb8 18.Nxg6
Vacating e5 so the square can be occupied by White's other knight, but the engines disapprove, suggesting 18.b5!?, 18.f5 or 18.g3.
18...hxg6 19.Ne5 Nd5
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| Both knights are well-placed |
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20.Ba6?!
Seeking to swop off White's good light-square bishop, but this is probably inadvisable at a time when White is saddled with a dark-square bishop that could be a liability in an endgame as it is hemmed in by its own pawns.
20...Rxc1 21.Bxc1
Forced, as the king's rook is needed to defend f4.
21...Rc8 22.Bxb7
It is difficult to safely withdraw the bishop, eg 22.Bd3 can be met by 22...Rxc1 23.Rxc1 Nxf4 24.Qe3 Nxg2. However, possible is 22.Nxg6!? fxg6 23.Bxb7 Qxb7 24.Qxe6+, but it seems the engines' 24...Kf8 25.f5 g5 wins for Black, although the position remains sharp.
22...Qxb7 23.Bb2
23.Nxg6!? fxg6 24.Qxe6+ transposes to the previous note.
23...Rc7 24.b5!?
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| How should Black respond to White's threat to play Nc6, blocking the open file? |
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24...Ne7
This may be best. Black could sacrifice the exchange with 24...Qc8 25.Nc6 Rxc6!? (25...a6 26.a4) 26.bxc6 Qxc6, but 27.Rc1 lets White fully mobilise, giving a completely equal position, according to the engines. The alternative pawn captures, 26...Bxf4 and 26...Nxf4, do not seem to be improvements. However the engines point out the possibility of temporarily sacrificing the knight with 25...Nxf4!?, when 26.Rxf4 Rxc6 27.bxc6 Bxf4 nets a pawn, although the position is not completely clear after the continuation 28.g3!? Bd6 29.Qc4. One point about the text is that, as well as preventing Nc6, it rules out Nxg6 ideas.
25.Qd2
The engines dislike this, suggesting 25.h4, or the pawn sacrifice 25.d5!? to liberate White's bishop. Either way, they reckon Black has at least the upper hand.
25...Qd5 26.Qb4?
This allows liquidation into an ending that White has little chance of holding, so the engines suggest 26.Qd3 or 26.Qe2!?, albeit agreeing White is anyway losing.
26...Rc2 27.Rf2
Both 27.Nf3? Bd6, and 27.Rf3? Bxe5 28.fxe5 (28.dxe5? Qd1+ 29.Rf1 Qe2) Nf5, are even worse for White.
27...Rxf2 28.Kxf2 Bxe5 29.dxe5
White's king is even more exposed after 29.fxe5?!
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| How would you assess this queen-and-minor-piece ending? |
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White's bad bishop and exposed king, combined with Black's good knight, make this a very good ending for Black, provided a) perpetual check is prevented, and b) queens stay on the board (at least until any resulting minor-piece ending is a trivial black win).
29...Nf5 30.g3?
UF was presumably worried about ...Nh4, but the engines give 30.Bc3!? as 30...Nh4 can be met by 31.Kg3! However, 30...Nh6 is strong, eg 31.Bd4 Qe4 32.Qd2 Qb1 33.Bb2 Qa2 34.h3 Qb3 35.Qe2 Nf5, when White is still hanging on, but the practical difficulties of defending such a position are huge.
30...Qd3
Probably even stronger is 30...Qh1.
31.Qc3!?
This is best, according to the engines, but now b5 falls.
31...Qxb5 32.Qd2 Qc5+ 33.Kg2 Ne3+ 34.Kf3 Nd5 35.Qc1!? Qb5
35...Qxc1?! may win, but it is a lot less clear than keeping queens on.
36.Kg2?!
This speeds the losing process, but White was anyway the equivalent of almost a rook down, according to the engines.
36...Qe2+ 37.Kh3 Ne3 0-1
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