White has not yet completed his development, and in the absence of the light-squared bishop, his pawn structure looks rickety.

This is the basis of Black’s whole idea. If he had to retreat the knight, White would entrench his knight on d4 and obtain the advantage, as the Bb7 would be too bad.

White also has a lot of weaknesses after 17.Bxd4 Bxf3 18.exf6 gxf6! 19.Bg1 Ba8.

White has a bad king, and his light squares are very weak – Black has a decisive advantage.

He would have won more quickly after 21...Rxc1 22.Rxc1 Bd2.

The position is extremely sharp, and both kings feel unsafe. In such positions, the cost of an error is very great, and even the greatest players cannot always find the decisive continuation. Finding the winning path for Black requires colossal effort. One idea that is obvious is pinning the Ng3 with the bishop coming to h4, whilst it is also tempting to eliminate the Nc4, since the rook on a5 is hanging, and there is an unpleasant check at d6. However, all Black’s efforts are dealt with by the queen, which occupies a great defensive position on e3 – it pins the Be6 and indirectly defends the Ng3, and is ready at the necessary moment to close the b8-h2 diagonal with the move f3-f4. The key to winning is to shift the queen from its ideal position, before making a decisive attack on the white pieces:

In the game, there occurred 28...Rxc4 29.bxc4 Bh4 30.Kf2 Qxc4 (on 30...Rg5, there follows 31.f4 – this is where we see the excellent position of the queen at e3!) 31.Qd4 Qxc2+ 32.Rd2 Qc5 – the endgame looks equal and ended in a draw.

Black wins easily after 29.Qe2 Rxc4 30.bxc4 Bh4 31.Kf2 Rg5 – there is not the move f3-f4, and the Ng3 is simply lost.

Taking with the king allows the black queen to be included in the attack with tempo: 31.Kxd1 Qd8+ 32.Ke1 Qd4 33.Rg2 Bf4 34.Nf1 Rh1 – Black completely dominates, and has the irresistible threat of 35...Kf8, followed by 36...Bh3.

With the irresistible threat of 34...Qf3.