Pranesh M vs Murali Karthikeyan: game review

18…Rxg5!! A real sacrifice: Black gives up material and the engine still rates it best.

• Puts the rook on g5 where it can be taken.
• White can take, but after 19.Qxg5+ Kh7 20.Qh4+ Kg7 the engine rates it 0.00.
• Takes the bishop on g5.
• 18…Rxg5 stops Bxf6.
• White was threatening Bxf6, winning the queen. Rxg5 takes care of it.
• White answers 19.Qxg5+, winning the exchange.

• The idea: 18…Rxg5!! gives up the rook on g5 to stay in the game: after it Black holds the balance (0.00); anything else leaves Black losing (+4.90).
• What Black gives up: 18…Rxg5 puts the rook on g5 where it can be taken by the queen on h4. That's a whole rook on offer.
• What it does instead: It takes the bishop on g5.
• If White takes the rook: 19.Qxg5+ is met by 19…Kh7, preparing …Nd5 and …Kg7. Then 20…Nd5 uncovers an attack on the queen on g5, and 23…Qf6 attacks the b2 pawn, which is undefended. Black is a piece down: Black holds the balance (0.00). This is White's best try.
• Without the sacrifice: The best move without the sacrifice, 18…Re6, is clearly weaker (+4.90 against 0.00). White answers 19.Rae1, threatening Rxe6, winning the queen. That would leave Black losing.

• Both sides followed opening theory up to 10…d6: 20 moves in all, 10 by White and 10 by Black.
• Theory runs out after 10…d6: too few games between strong players reached this position to go further.