Lucena Position Practice: Build the Bridge

Watch the method: press play to see the winning idea run, or step through it move by move.

If rook endings are the most common endings in chess, the Lucena is their capital city: rook and pawn versus rook, pawn on the seventh, attacking king in front of it. Every winning technique funnels here.

The problem. Your king sits on the promotion square, and the defending rook checks forever from behind. Step out along the file and the checks follow; block with your rook too early and the defender's king walks back.

The bridge. (1) Rook to the FOURTH rank, the key move that looks mysterious until the very end. (2) A rook check drives the enemy king one more file away, which finally frees a square for your king. (3) King steps out toward the middle. (4) The checks begin: the king walks down the board... (5) ...and lands next to the rook, which now blocks the check while shielding the pawn's promotion. The 'bridge' is a roof of rook and king under which the pawn queens.

Boundary conditions. The technique needs a non-rook pawn (a knight, bishop or centre pawn; rook pawns are a different story) and the defending king cut off by at least one file. And the drill steps in only when releasing the cut actually costs the win: here 1.Rd1+ leaves the c-file and is still one of the fastest wins, while 1.Ra1 is the real blunder, since 1...Rxa1 leaves White stalemated.