Yuri Shulman v Irina Krush, US championship, Stillwater, Oklahoma 2007. This year’s title contest lacked the sponsorship from a Californian millionaires consortium which provided huge prize funds, but the winner still earned $20,000 from a respectable $60,000 total. The women competitors, who had shone in previous championships, ran into trouble at the start, notably in today’s position. Krush’s king is perilously situated at f6, but her queen and bishop look solid defenders so that the former Ukrainian was dreaming of counterplay down the g file against the white king. White’s next turn showed that Shulman had it all worked out and, against Black’s plausible replies, led to a sudden checkmate. What happened?