Bishop and Pawn vs Knight: Winning by Zugzwang

Bishop, pawn and king against a bare knight is a common ending, and the result hangs on a single question: can the stronger side put his opponent in zugzwang? If not, the knight holds.

The bishop cannot escort this pawn. It is light-squared and d8 is dark, so it will never guard the queening square. That job belongs to the king, which already stands on e7. The bishop is free to hunt the knight instead.

Only Bb3+ wins. After Kc5, Ba2 keeps the bishop where it belongs, but Black is not in zugzwang yet: he still has Kc6 and Ng4. From the a2-g8 diagonal the bishop covers d5, e6, f7 and g8, which is exactly where the knight and king want to go, and the zugzwang lands only at the end, when the bishop swings Bf3-e4 and every black move loses.

Why the win exists at all. A knight only holds this ending when it can shuffle out of the king's reach. Here it cannot: with your king on e7 the knight on f6 is boxed into a tiny orbit, so once the bishop finishes the squeeze, handing Black the move leaves it no safe square. Let the king wander and the knight relocates to h7 and f8, and the zugzwang is gone.

The two ways to spoil it. Pushing d6-d7 loses the pawn to Nxd7, and Kxf6 reaches bishop against king. Every move other than Bb3+ lets Black off with a draw.

In this drill you face a defence that never cracks. Squeeze the knight, hand Black the move, and only then push.