Sicilian Defense Closed Back Rank Mate Puzzle (Rated 890): Spot Back Rank Mate — One-Move Finish

This puzzle is a classic back rank mate pattern in a middlegame setting. The key idea is that the enemy king is boxed in by its own pawns and pieces, leaving the first rank vulnerable to a rook invasion. Even when the position looks busy with hanging pieces and tactical tension, the decisive factor is king safety: if the king has no flight squares and the back rank is weak, a single rook move can end the game immediately.