In playing his last move (17.g4-g5), White missed a tactical nuance:

Both the Bf4 and the b1-h7 diagonal are hanging.

In the variation 19.Nd4 dxe4 20.Qxe4 Bc5 21.c3 Bg4! 22.Rd2 Bf5 23.Qxf5 Qxf5 24.Nxf5 Bxg1, White again loses because of the pin, only this time on a different diagonal.

Black wins a pawn, in addition to which he has the advantage of bishop over knight, and the more active major pieces – White’s position is hopeless.

White resigned.

The Nd4 is pinned, which gives rise to a tactical motif:

First, increasing the pressure and forcing the Nd6 to leave its active position. The immediate 31...Be2, with the same idea, was also possible, but after 32.Rxc5 Bxd1 (on 32...Qxc5, there also follows 33.N6f5) 33.N6f5, the position remains dynamic, and the realisation of the advantage is more difficult. In the game, Black played very poorly, not even trying to exploit the pin, and after 31...Ne4 32.Nxe4 dxe4 33.Nf5 Rxa2, a double-edged position arose.

Because of the back-rank mate, retreating to d2 is impossible, and so White loses material. After

White has to surrender the exchange:

Black is winning easily.