Coincidence?

Readers of "Blitz Luck" had no difficulty solving the problem that I posted there. Consequently, they should find Karpov's move in this position from his game against Spassky in the 1975 Soviet Team Championship.

White to move


It was a happy coincidence that I examined this game briefly last weekend, then on Wednesday found myself in the blitz position posted that evening. The game appears in the list of Karpov's one hundred best games. I am going through them via the software The Best of Chess Informant: Anatoly Karpov.