Test Position: Nikolic Fischer revisited 19...Bg4!!

[Modern Times]

Komodo 1318 dev doesn't find it after nearly 10 hrs. It starts with a6, and moves to Nf3+ at depth 31. At depth 37 it did look at h4 among other moves, but didn't prefer it:

37.01 569:21 0.00 1...Nf3+ 2.Bxf3 Bxf4 3.Bg2 Bb8 4.a6 h4
5.axb7 Qxb7 6.Be1 cxb5 7.Rxb5 Qc8
8.f4 exf3 9.Qxf3 Qe6 10.Rb7 Ne4
11.Nxe4 dxe4 12.Qd1 Qc4 13.Rxf5 gxf5
14.Qh5 hxg3+ (312.876.705.089) 9158
TB:765.575

best move: Ng5-f3 time: 586:55.688 min n/s: 9.157.647 nodes: 322.492.939.753 TB: 765.575

[gerold]

Strelka 6 didn't fined Bg4. If Bg4 is played Strelka 6 finds the win after 58 moves. White resigned.

[rabbits23]

Gerold : Just as a matter of curiosity how does Strelka 6 go about getting
the win for Black after the bishop sacrifice? Does it set about getting the
rooks on to h8 and h7 and bringing the queen into the action via g4? Or
does it do it differently?
Regards Allan

[gerold]

Gerold : Just as a matter of curiosity how does Strelka 6 go about getting
the win for Black after the bishop sacrifice? Does it set about getting the
rooks on to h8 and h7 and bringing the queen into the action via g4? Or
does it do it differently?
Regards Allan

After 19...Bg4.

1.h3xg4...h5xg4
2.Rf1-h1...Ng5-f3+
3.Bg2xf3...g4xd3

etc.

22 moves after Bg4 before a minus score for white.

P.S. R does go to h8 and b8 and Qg4.

[gerold]

Gerold : Just as a matter of curiosity how does Strelka 6 go about getting
the win for Black after the bishop sacrifice? Does it set about getting the
rooks on to h8 and h7 and bringing the queen into the action via g4? Or
does it do it differently?
Regards Allan

Yes Black rooks goes to h8 and h7 and Qg4. Very nice play by black.

[Vinvin]

Gerold : Just as a matter of curiosity how does Strelka 6 go about getting
the win for Black after the bishop sacrifice? Does it set about getting the
rooks on to h8 and h7 and bringing the queen into the action via g4? Or
does it do it differently?
Regards Allan

After 19...Bg4.

1.h3xg4...h5xg4
2.Rf1-h1...Ng5-f3+
3.Bg2xf3...g4xd3

etc.

22 moves after Bg4 before a minus score for white.

P.S. R does go to h8 and b8 and Qg4.

After 19. ... Bg4 20. hxg4 hxg4 21. Rh1 Nf3+ 22. Bxf3 gxf3 Stockfish want to play a subtle move (because 23.Nh3 gives advantage to black) : 23.Nd3!, it's seems to be = .

[Event "e"]
[Site "s"]
[White "w"]
[Black "b"]
[Result "*"]
[FEN "r3r1k1/pp1q1p2/2p2npb/PPPp1bnp/3PpN2/2N1P1PP/1R1B1PBK/3Q1R2 b - - 0 19"]

19. ... Bg4 20. hxg4 hxg4 21. Rh1 Nf3+ 22. Bxf3 gxf3 23. Nd3 (23. Nh3 Kg7
24. Kg1 Rh8 25. Qf1 a6) 23. .. exd3 24. Qxf3 *

3 best moves after 24.Qxf3 :

FEN: r3r1k1/pp1q1p2/2p2npb/PPPp4/3P4/2NpPQP1/1R1B1P1K/7R b - - 0 24
30/47 03:10 345.880k 1.813k +0,46 24. ... Ce4
30/47 03:10 345.880k 1.813k 0,00 24. ... Rg7 25.a6 b6 26.bxc6 Dxc6 27.Rg2 Fg5 28.cxb6 axb6 29.Dd1 Txa6 30.f4 Fh6 31.g4 g5 32.Df3 De6 33.f5 Dc6 34.Dh3 Th8 35.Dg3 Dd7 36.De5 Te8 37.Dg3 Th8
30/47 03:10 345.880k 1.813k 0,00 24. ... Fg5 25.Dg2 Rg7 26.a6 b6 27.Rg1 cxb5 28.f4 Fh6 29.Txb5 Ce4 30.Cxe4 Dxb5 31.Cd6 Db3 32.Cxe8+ Txe8 33.cxb6 Dd1+ 34.Rh2 Dh5+ 35.Rg1 Dd1+

[BeyondCritics]

Very good. This position is tasty and the attacking scheme of black appears typical for this system (h5, Ng5 etc..). The position seems therefore well worth studying.

I explored this with stockfish and can testify that this is an immedeate win for black in any case after 19..Bg4.
Since if 20.hxg4 hxg4 21.Rh1 (what else?) Nf3+ 22.Bxf3 gxf3 there is no escape
[d]r3r1k1/pp1q1p2/2p2npb/PPPp4/3PpN2/2N1PpP1/1R1B1P1K/3Q3R w - - 0 23
For a long time stockfish believes to slip away with 23.Nd3!? but after 23...Kg7! 24. bxc6 bxc6!? 25.Ne5 Ng4+ 26.Kg1 Nxe5 27.dxe5 stockfish finds the finish on its own from here quickly. Other tries are futil either.
I think it is instructive and fun to eplore the "critical" line after 23.Nh3 Kg7! 24.Kg1 Rh8 with computer assictance
[d]r6r/pp1q1pk1/2p2npb/PPPp4/3Pp3/2N1PpPN/1R1B1P2/3Q2KR w - - 4 25

Alternatively white can deny the sacrifice with 20.Qa4, dreaming of bxc6 and Rfb1 with counterplay... How do you finish the task quickly:
[d]r3r1k1/pp1q1p2/2p2npb/PPPp2np/Q2PpNb1/2N1P1PP/1R1B1PBK/5R2 b - - 2 20

[Vinvin]

...

Amazingly deep !
I'll do an overnight analysis.

[rabbits23]

Yes Oliver I agree with your your thoughts on the position and the rest of
the variations in the game. To me the game highlights just what a
brilliant chess player Fischer was.
Allan

[rabbits23]

Oliver: If white had refused the Bishop sacrifice I imagine Fischer would
have had some other clever plan to win the game. I haven't looked at
the variations after 20) Qa4 but will explore a few over the next couple
of hours
Allan