Black has incautiously placed his queen on c7, which White exploits:

White has not only an extra pawn, but an active rook, which is no less important.

Now, the advance ...a6-a5 is impossible, and the black rook remains in a passive position.

This attempt to get active is doomed to failure, since he has no targets on the kingside – the f2-pawn is not only defended, but ensures an excellent post on e3 for the bishop.

With the help of a tactical blow, White ensures himself a pair of connected passed pawns on the queenside. However, even one passed pawn, supported by the bishop, should be enough to win.

Black resigned, since after 36...fxe6 37.Rxb5 Rxa3 38.Rh5+, he will lose a bishop.

Black thought his knight on h5, which is heading for f4, was safe. If White plays...

then

and after taking the knight on h5, the white pawn on d4 hangs. However, White has the zwischenzug.

The Nh5 still hangs, whilst there is now a threat of 21.d6. White has a healthy extra pawn, and went on to win.

Losing the Bd8, which is X-rayed down the d-file by the white rook, would obviously be catastrophic for Black, because he would be unable to get out his queenside pieces. The only question is where the white knight should go, and the answer is easy to find: