Black to play. This is from Karpov-Korchnoi, Dortmund 1994. In this unusual position Karpov has two queens but Korchnoi’s forces coordinate much more efficiently. His next move led to a decisive material gain. Can you see it? Answers via email to victoria@spectator.co.uk by Tuesday 17 July. There is a prize of £20 for the first correct answer out of a hat.