On 15.Be3?, Black had prepared 15...a4 16.Bd5 b4„.

On 15...hxg6, there is 16.Be3 a4 17.Bh6!. Opening the h-file has given White a large advantage.

After 16...Rxf7 17.gxf7+ Kxf7 18.Ne2! followed by Nxd4, the black king faces a difficult future.

17...h6? 18.Qxd6 b4 19.e5 Ng8 20.Ne4+–.
17...b4? 18.Qxf6 Qxf6 19.Rxh7#.

White wins in beautiful fashion after 19...bxc3: 20.Kb1!! Rb8 (20...Bf8 21.Qg3 Qb6 22.b3 a4 23.Qg6 Be7 24.e5+–; 20...cxb2 21.e5 Qc7 22.Qxc7 Rxc7 23.exf6 Bf8 24.Rh5 Bc6 25.Rc5 Bxc5 26.Rd8+ Bf8 27.Rxf8#) 21.b3 Rb6 22.Qd4 a4 23.Qxa4 Qf8 24.Rxd7 Nxd7 25.Qxd7 Rf6 26.Rd1 Rxf7 27.Qd8!±.

Threatening 22.Rxh7.

The rest is simple, as the black pieces can defend neither their king nor even themselves.

Black resigned.

White needs to develop his play on the queenside. If he begins the preparation for the advance of the b-pawn with the move a2-a3, then after b2-b4 he will need further preparation of the advance b4-b5 with the help of the a-pawn, and will have to spend additional time defending b4. Foreseeing this, White chose...

Played in one move, and winning a precious tempo.