Chess puzzle #31: comeback kid gets crushed

Former world champion Boris Spassky was completely outmaneuvered in his game against Anatoly Karpov in Montreal (1979). See the diagram.

Black just played 38 … b5? This is a mistake after white can finish the game with a bang. What is the winning move in this position?

After you clicked on the link you will find the complete game. It is a fine positional achievement and a model game on the subject ‘how to play against the isolated queen pawn’. Spassky was nick named ‘the comeback kid’. But here there was no coming back. Spassky was rendered completely helpless against white’s clever play.