Monday 2 December 2019

Blackmar-Diemer Gambit

Spanton (1934) - Julio Domingo Mortalla (1718)
Benidorm Round 4
1.e4 d5 2.d4 dxe4 3.Nc3 Bf5!?
Unusual, but it has been played by grandmasters.
4.f3
4.g4!? Bg6 5.Bg2 was played by Diemer in a 1972 win.
4...Nf6
The game has transposed to one of the main lines.
5.g4!?
More popular is 5.fxe4 Nxe4 6.Qf3 Nd6 7.Bf4, when neither Komodo10 nor Stockfish10 reckon White has full compensation for his pawn deficit.
5...Bc8!?
The engines prefer 5...Bg6 6.g5 Nd5 with what they reckon is a slight edge for Black, but they do not regard the text as ridiculous.
6.g5!
This appears to be a new move, or at least is not in ChessBase's 2020 Mega database. I rejected the known move 6.Nxe4? because of 6...Nxe4 7.fxe4 e5.
6...Nd5 7.fxe4 Nxc3 8.bxc3 c5 9.Nf3 e6 10.Bg2 Be7 11.0-0 0-0 12.Be3
I rejected 12.Bf4, which is liked by the engines, because of 12...Bd6, when Stockfish10 reckons 13.e5 gives White a large advantage, but Komodo10 has Black equal.
12...Qc7 13.Qe2 b6 14.d5 exd5 15.exd5 Bd6 16.c4 Bg4 17.h3 Bh5 18.Qd2 Nd7 19.a4?!
The engines prefer 19.Nh4 g6!? 20.Bf3 Bxf3 21.Nxf3 with a slight edge for Black.
19...Bxf3 20.Bxf3 Ne5 21.Be2 Ng6
The engines reckon Black is still better after this retreat, but they prefer 21...Qd7, with lasting pressure against White's airy king.
22.a5 Rae8 23.axb6 axb6
Not 23...Qe7? 24.bxa7 Qxe3+?? 25.Qxe3 Rxe3 26.a8=Q.
24.Bd3 Nh4?!
Black has an edge after 24...Re7, according to the engines.
25.Bf4 Re7?!
The engines give 25...f6 26.Bxd6 Qxd6 as equal.
26.Qf2
26.Ra7!? Qxa7 27.Bxd6 is slightly better for White, according to the engines.
26...Bxf4!?
During the game, I thought this was a mistake and that Black should have played 26...Ng6, but the engines prefer White after 27.Ra7!?
27.Bxh7+ Kxh7?
We both missed that after 27...Kh8 28.Qxh4, Black has 28...Bxg5! 29.Qxg5 Kxh7 with equality, according to the engines.
28.Qxh4+ Kg8 29.Rxf4 
29.Qxf4!? may be slightly better for White.
29...Rfe8 30.Raf1 Qe5?
30...Re2 gives Black full compensation for the pawn, according to the engines.
31.Qg3 Rd8 32.h4
32.g6!? Rd6 (32...fxg6?? 33.Qxg6) 33.gxf7+ Rxf7 34.Qg4 Rxf4 35.Rxf4 seems even stronger.
32...b5!? 33.cxb5
The engines give 33.Qf3!? bxc4 34.Rxf7 Qe3+ 35.Qxe3 Rxe3 36.R1f5 with a slight edge for White.
33...Rxd5 34.c4 Rd4 35.Qf3 Rdd7?
I expected 35...Rd2, when Stockfish10 reckons Black has full compensation for the pawn, but Komodo10 gives White a small edge.
36.Qf2?
The engines reckon 36.Qg4 is better.
36...Qc7?
More passivity by Black. 36...Rd3 is equal, as is 36...Qc3, according to the engines.
37.Rb1?
37.Qg3 seems best, eg 37...Rd4 38.g6 fxg6 39.Rf8+ Kh7 40.Qxc7 Rxc7 41.R8f4.
37...Rd4?
...Rd3 was again good, as is 37...Qe5.
38.Rxd4 cxd4 39.b6 Qb7 40.Qxd4 Rd7?
The engines give 40...Re4!? 41.Qd8+ Kh7 42.Qd5 Qe7 43.Kg2 Rxh4 44.Rh1 Rxh1 45.Kxh1, when Black seems to have a perpetual starting with 45...Qe1+.
41.Qf2 Qe4 42.Re1 Qg4+
Can you find a win for White?
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43.Qg2?
I rejected 43.Kh2! because of 43...Rd3, missing that after 44.Re8+ Kh7, White has 45.Re3 Rxe3 46.Qxe3 Qxc4 (46...Qxh4+?? loses to 47.Qh3 ) 47.Qf3, which wins for White.
43...Qd4+?
43...Qxc4 gives good drawing chances, thanks to White's exposed king.
44.Qf2 Qg4+ 45.Qg2? Qd4+? ½–½

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