No. 726

White to play. Salov-Horvath, Groningen 1983. In this treacherous rook and pawn endgame, White found the only winning move. What did he play? Answers should be emailed to chess@spectator.co.uk by Monday 31 October. There is a prize of £20 for the first correct answer out of a hat. Please include a postal address and allow six weeks for prize delivery.

Last week’s solution 1 Nd5! Qxd2 2 Nc7#. But not 1 Nb5 Qb6!

Last week’s winner John Boyd, Ashtead, Surrey