TCEC Season 18 This is not a SuFi Bonus Game 40: Stockfish-LeelaCPU
|Game||Season 18, This is not a SuFi Bonus, Game 40|
|Links|| TCEC archive|
The second Grob game of the Season 18 "This is not a SuFi" bonus event. Here, Stockfish and Leela played openings from Superfinals of past seasons following the format of playing the openings from both sides. This opening is from Season 12 Superfinal between Stockfish and Komodo, games 45 and 46. Both these games ended also in black wins, as well as the first Grob game in the "This is not a SuFi" bonus event .
Notably, Leela played on CPU in this game being perhaps 100 Elo lower rated than Stockfish. The time control was 2 hours with 10 seconds increment per move.
End of the opening book.
|Position after 11... Nf6|
1... d5 2. e3
A rare move in the rare opening, only 2 games by titled players in the Lichess masters database. Stockfish has a very different approach to the Grob opening compared to Leela, playing the Grob solidly and covering the g4-pawn with the queen.
Leela played the Grob gambit here (2. Bg2). But if the gambit was to be avoided, perhaps it was better to protect g4 by plaing 2. h3, instead. With 2. e3 the game resembles the French defense with reverse colors and an extra g4.
2... Nc6(N) 3. d4 e5 4. Nc3 Be6 5. dxe5 Nxe5 6. h3 h5 7. Nf3
White gives up a pawn in order to avoid black getting the rook into play early. A line such as the following would be problematic: 7. gxh5 Nf6 8. Nf3 Rxh5 9. Nxe5 Rxe5 10. Qd4 Nd7 11. Bd2 Bc5 12. Qf4 d4 with a dangerously strong initiative for black.
7... Nxf3+ 8. Qxf3 hxg4 9. hxg4 Bxg4 10. Qg2
Taking the bishop would lose the exchange, of course: 10. Qxg4?? Rxh1
10... Rxh1 11. Qxh1 Nf6 (diagram)
The black bishop on g4 is now annoying, preventing white from castling.
|Position after 27. bxc3|
12. Bd2 Qd6 13. Qg2 O-O-O 14. f3
White needed to do something to prepare for long castling. 14. f3 is not a move one really wants to play here, but the alternatives were not any better. For example: 14. Be2 Bxe2 15. Nxe2 Ne4 16. O-O-O and black is clearly ahead in development and the white queen is somewhat cut off from the likely forthcoming queenside action.
14... Be6 15. Nb5
Given the opportunity, white decides to go for some activity and reroute the knight to the center and push the a-pawn.
15... Qb6 16. a4 a6 17. a5 Qc5 18. Nd4
White could have been more aggressive by pushing the b-pawn: 18. b4 Qe7 19. Nd4. But given white's already dubious king safety, opening up the queenside could prove overly double-edged. But on the other hand, trying to play solidly is problematic, too.
18... Bd7 19. O-O-O
After both sides have managed to castle, white is a pawn down with a somewhat worse pawn structure. Here, barring blunders, basically only black is playing for a win.
19... Re8 20. Kb1 Kb8 21. Nb3 Qe7 22. Re1 g6
A necessary move to allow the bishop on f8 to develop instead of defending the g7-pawn.
White begins to add some pressure to the knight on f6, asking black to do something about it sooner or later. On one hand, a move such as Nh5 would misplace the knight a bit, and on the other hand, Bg7 would put the bishop under a pin. This move has also a more subtle plan behind it, to move the white queen to the queenside via d2 and d4. Here, Qd4 is with a tempo, since black needs to address the question of Nf6. Black responds by making room for the bishop on f8 to enter the game.
It should be noted that the tempting 24. Qg5 is not a threat because of tactics. For example, 23... Ka8 (placeholder move) 24. Qg5? Ne4! 25. Qxe7 Nxc3+ 26. bxc3 Bxe7. Black has the bishop pair and better pawn structure with an extra pawn.
23... Qe6 24. Qd2 Bd6 25. Qd4 Be5
Black answers to the question of Nf6 in a somewhat creative manner. While white now gets the queen to the queenside, black forces the exchange of a bishop exchange and gets to keep the knight on f6. The bishop exchange also avoids any opposite-color bishop endings.
26. Qb4 Bxc3 27. bxc3 (diagram)
Here white chose the more energetic option over the more solid 27. Qxc3, maintaining the absolute pin on the b-file while opening it. While this yields up some attacking initiative, it comes with a compromise to the health of white's pawn structure. But already a pawn down with a somewhat worse position, perhaps this was the right choice.
The black king sidesteps the pin, which perhaps is the most natural decision.
|Position after 38... cxd6|
27... Ka8 28. Nc5 Qc6 29. Bd3
White didn't take the bishop with 29. Nxd7 Nxd7 as simplifications here favor black a bit.
The bishop now guarding the b7-pawn releases the black queen. Black now threatens favorable simplifications with Qd6 and Nd7, which prompts the white knight to vacate the c5-square.
30. Nb3 Qe6 31. Kb2 Nd7 32. f4 Qf6 33. Re2 Kb8 34. Re1 Ka8 35. Nc5 Nb8
Black reroutes the knight to a better square of c6, in where it also keeps an eye on the pawn of a5. Importantly, this ties up white resources to defend the pawn.
Here the knight exchange is not that favorable for black, as it would dislocate the black pieces temporarily. Although the exchange should not be that bad, either: 35... Nxc5 36. Qxc5 Qd8
36. Nb3 Nc6 37. Qc5 Qd6 38. Qxd6 cxd6 (diagram)
After the queen exchange, now the point of Nc6 becomes clearer. It keeps the white counterpart in a more passive square. Without the white knight, black's doubled pawns are difficult to attack, as the white rook is also tied on defensive duties for the pawn on e3.
|Position after 51... Rh8|
The white king needs to relieve the white rook from defending the pawn on e3.
Again, simplifications here would favor black: 39. c4 dxc4 40. Bxc4 Be6.
39... Kb8 40. Kd2 Rh8
Now as the king arrived to defend e3, relieving the rook, black takes the opportunity to claim the open h-file.
41. Ke2 Kc7 42. Rg1 Rh3 43. Kf2 Bd7 44. Re1 Bg4 45. Bf1 Rh1
Black practically forces one more piece trade by luring the king to g2, far away from protecting the vulnerable c2 pawn. Black's threat is to play Bf5, essentially transposing to the game continuation.
46. Kg2 Rh5 47. Bd3 Bf5 48. Bxf5 Rxf5 49. Ra1 Rh5 50. Nd4 Kd7 51. Ra4 Rh8 (diagram) 52. Kf3 Rc8
Black takes advantage of the white king being lured to the kingside and shifts the focus back to the c-file. This ties the white pieces to defend the a5/c3 pawns.
|Position after 81. Ra8|
53. Ne2 Nd8
Black is now threatening to play Rc5 and then Nc6 back, winning the pawn on a5. To delay losing the a5-pawn, white temporarily sacrifices the f5-pawn with some kingside rook activity.
54. f5 gxf5 55. Rf4 Nc6 56. Kf2
The response to 56. Rxf5 would have been 56... Ne5+ after which white would have likely played 57. Kf2, transposing back to the game.
The straightforward 56... Nxa5 was just as winning.
57. Rxf5 Ne5 58. Ke1 Rc5 59. Rf1 Rxa5 60. Kd2 Rc5 61. Nf4 Rb5 62. Nd3 Ke7 63. Nf4 a5 64. Ra1 Kd7 65. Kd1 Nc4 66. Ke2 Ne5 67. Kd2
Sometimes Leela has trouble choosing a move when multiple equally winning moves are available. Winning with two pawns up with an outside passer is straightforward technique for these engines.
67... Rc5 68. Rb1 Kc6 69. Ra1 Kd7 70. Rd1 Kc6 71. Ra1 b6 72. Nd3 Rc4 73. Rf1 Rh4 74. Kc1 Nc4 75. Nb2
Trying to avoid losing another pawn with 75. Re1 was not any better: 75... Rh3 76. e4 dxe4 77. Rxe4 Rh1+ 78. Ne1 is hopeless for white.
75... Nxe3 76. Re1 Nc4 77. Kb1 Nxb2 78. Kxb2 d4 79. cxd4 Rxd4 80. Re8 Kd7 81. Ra8. 0-1 (diagram)
Black wins by the TCEC win rule.
Perhaps pushing the f-pawn would be the easiest victory for black, as white simply cannot stop the black pawns advancing on different sides of the board. For example: 81... f5 82. Rf8 f4 83. Kc3 Re4 84. Kd3 d5 85. Rf5 Ke6
86. Rf8 a4 87. Rb8 a3 88. Rxb6+ Ke5 89. Ra6 f3 90. Ra8 a2 91. Re8+ Kf6 92. Rf8+ Ke7 93. Ra8 f2 94. Ra7+ Kf6 95. Ra6+ Kg5 96. Rxa2 f1=Q+.