Closing The Gate

By looking at the position, one can tell that white’s game is nearing to an end. But a simple move by white shocked black’s camp. Lutskovsky-Gridnev (1976)

Solution: 1. g4! Resign. Winning in any variation. Black’s queen is en prise and at the same time blocking the diagonal of black’s queen protecting Rc8+. The move 1. Re1+ 2. RxR still threatening mate via Re8. Swindle as it is.