no. 521

White to play. This is from Mamedyarov–Georgiadis, Biel 2018. Many of Mamedyarov’s games feature a kingside attack based upon a powerful bishop on the b2-square. Here, his next move led to a decisive increase in pressure against the black king. What was it? Answers to victoria@spectator.co.uk by Tuesday 4 September. 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 Qxd3
Last week’s winner James Payne, Barnby, Suffolk