DenLaz vs Zhigalko_Sergei: game review

20…Qc7 is a mistake: Black's winning chances go from 50% to 39%.

• White answers 21.Bxh6, which takes the pawn on h6.
• After Bxh6, White wins 1 point of material within 2 moves.
• Better was 20…Qe7 (0.00).

Better: 20…Qe7 prepares …hxg5 and …Reb8. Engine line: 21.g5 hxg5 22.Bxg5 Reb8 23.Rf3 d5 (0.00).

21.Bxh6!! A real sacrifice: White gives up material and the engine still rates it best.

• Puts the bishop on h6 where it can be taken.
• Taking is too dangerous: Black's best reply is 21…Nh7 22.Be3 Bd4 23.Qd2 instead (the engine rates it +1.56).
• Takes the pawn on h6.
• 21.Bxh6 threatens Qg5, with mate in 5, and wins a pawn.
• It threatens Qg5, with mate in 5, so Black has to spend the next move on it.
• Takes the h6 pawn and wins a pawn once the captures settle.

• The idea: 21.Bxh6!! offers the bishop on h6. Taking it gives White an attack worth more than the bishop.
• What White gives up: 21.Bxh6 puts the bishop on h6 where it can be taken by the g7 pawn. That's a bishop on offer.
• If Black takes the bishop: 21…gxh6 is met by 22.Qxh6, taking the h6 pawn and threatening Qg5+, winning a knight. Then 23.b4 threatens bxc5, winning a bishop for a pawn. White is still a pawn down, but the attack is worth more: White is clearly better (+1.85).
• Black's best try: Black's best is to leave the bishop alone and play 21…Nh7. White answers 22.Be3, and the bishop on h6 gets away. Then 24.Bxd4 takes the bishop on d4, and 25.Qxd4 takes the d4 pawn. White ends up two pawns ahead: White is clearly better (+1.56).
• Without the sacrifice: The best move without the sacrifice, 21.Na4, is clearly weaker (+0.96 against +1.56). Black answers 21…Bd4, planting the bishop on the d4 outpost. That would leave White a little better.

24…Be6 is a mistake: Black's winning chances go from 46% to 36%.

• White answers 25.Ne2.
• Better was 24…Qd8 (+0.47), which brings the queen, Black's least active piece, into play (from 3 to 9 usable squares).

Better: 24…Qd8 brings the passive queen into play. After 25.Na4 Bd4 26.g5 c5 27.Nc3 Rxb3 28.Rxb3 Rxb3 29.Qf1 Nxg5 30.Rg3, the rooks are traded and Black comes out two pawns up (+0.47).

26…Bd4 is a mistake: Black's winning chances go from 31% to 19%.

• White answers 27.Nh5: adds a decisive attacker on the f6 pawn: 2 attackers against 1 defender.
• After Nh5, White wins 1 point of material within 4 moves.
• Better was 26…Qf7 (+2.18): shores up the f6 pawn, which was under as much attack as it had defence (1 against 1).

Better: 26…Qf7 shores up the f6 pawn. Engine line: 27.Nh5 Qg6 28.Bd2 Bb6 29.Qf1 Bd8 (+2.18).

27.Nh5! The only good move here: every alternative is clearly worse.

• Adds a decisive attacker on the f6 pawn: 2 attackers against 1 defender.
• The next best move, 27.Nf5, would drop White's winning chances from 81% to 69% (+2.12).
• 27.Nh5 wins a pawn, picking it up with 28.Nxf6+.
• Sets up a sequence and wins a pawn once the captures settle, picking it up with 28.Nxf6+.
• Black answers 27…a4.
• After 27…a4 28.Nxf6+ Kh8 29.b4 c5 30.b5, White comes out a pawn up (+4.39).

28.Nxf6+!! A real sacrifice: White gives up material and the engine still rates it best.

• Puts the knight on f6 where it can be taken.
• Taking is too dangerous: Black's best reply is 28…Kh8 29.g5 Qf7 30.Nxh7 instead (the engine rates it +4.56).
• Takes the pawn on f6.
• Creates a passed pawn on g4: no enemy pawn can stop it any more.
• 28.Nxf6+ wins a pawn.
• Takes the f6 pawn and wins a pawn once the captures settle.

• The idea: 28.Nxf6+!! offers the knight on f6. Taking it gives White the material back and more.
• What White gives up: 28.Nxf6+ puts the knight on f6 where it can be taken by the queen on e7 and the knight on h7. That's a knight on offer.
• If Black takes the knight: 28…Nxf6 is met by 29.Qg5+. Then 30.Rxf6 takes the knight on f6, and 32.Bg5+ gives check. Material is level and White is winning (+4.58).
• Black's best try: Black's best is to leave the knight alone and play 28…Kh8. White answers 29.g5, pushing the passed pawn to g5. Then 30.Nxh7 takes the knight on h7, and 31.Rf6 attacks the bishop on e6, which is undefended. White ends up a pawn ahead: White is winning (+4.56).

29.Qg5+! The only good move here: every alternative is clearly worse.

• The queen joins the attack: it now hits 2 squares around the Black king.
• Adds a decisive attacker on the knight on f6: 2 attackers against 1 defender.
• The next best move, 29.Bg5, would drop White's winning chances from 91% to 48% (−0.20).
• 29.Qg5+ wins a knight for a pawn, picking it up with 30.Rxf6.
• Sets up a sequence and wins a knight for a pawn once the captures settle, picking it up with 30.Rxf6.
• Shores up the g4 pawn, which was under as much attack as it had defence (2 against 1).

• Both sides followed opening theory up to 5.Bd2: 9 moves in all, 5 by White and 4 by Black.
• Black left the book with 5…a5. In 86 games from this position, strong players played 5…O-O (79%) or 5…d5 (10%).
• The main line goes on 5…O-O 6.g3 Re8.
• From here White scored 46% in those games, with 18% drawn.