Black has no way of meeting the white attack, and so he resigned.

The knight on d5 takes the important c3-square from the white bishop, and blockades the pawn on d4, which only disturbs White, by restricting his minor pieces.

He could also keep the advantage with 39...Bb4, threatening to penetrate the white position from the queenside.

More tenacious is 40.Qb2, but even then, after 40...Qe1+ 41.Kg2 h5!...there is a threat to break up the white kingside with ...h5-h4. At the same time, 42.h4 loses to 42...Bxh4! 43.gxh4 Qe4+ 44.f3 Qxh4, and Black develops a decisive attack.

White resigned, without waiting for 41...Be3 42.Qg2 Bxf2+ 43.Qxf2 Qxb3 – the superiority of the knight over the bishop is too great.

The black king is under close attention from the white pieces, and is defended only by pawns and the Be7. An important potential defender is the queen on e8, which, after a possible sacrifice by White, is prepared to join the defence after a move of the f-pawn. Thinking along these lines, one can find the typical blockading idea...

but the main point is seen at move 23 (20.Ne3 was played in the game).

There is only perpetual check after 22.Nxh7 Kxh7 23.Qh5+.

This is the key idea. After...

the decisive role in the attack is assumed by a modest pawn, which has already gone from b2 to d5. Despite Black’s even formally having a material advantage, it is not hard to see that his position is collapsing.