Exploiting his numerical superiority on the queenside, Black sacrifices a pawn to create a passed pawn.

Unable to sustain the pressure of the battle. White could hold a draw by 35.Rc6! c3 36.Be2+ Ka5 37.Rxf6 Bxf6 38.Bd1 Kb4 39.Kf3 Ka3 40.Ke3 Kxa2 41.Kd3 Ka3 42.d6 Kb4 43.d7 a5 44.Bf3 Kc5 45.Bd1 Kb4 46.Bf3 Be7 47.Bd5 f6 48.Bg8 h6 49.g4=.

In this version, the opposite-coloured bishop ending is lost.

39.Kf1 Kb4 40.Ke1 b5 41.f3 Ka3–+.

If White succeeds in lifting the blockade on d6, his passed pawn will become very strong. He can do this with his knight, for example via d2 to c4. Therefore, Black starts play on the dark squares:

With this move, Black gets rid of an ‘unnecessary’ piece, and not only strengthens his blockading knight, but the whole complex of dark squares. It is important that now the white Bf3 becomes a bad piece, blocked in by its own d5-pawn.

A serious positional mistake, after which White is left with a bad bishop against a beautiful knight. It was essential to decline the exchange, and retreat the bishop to d2 or e3 – in this case, White would retain counterplay, since then Black does not get a free hand for major-piece play on the dark squares.

After an exchange of dark-squared bishops, outposts appear on e5, e3 and g5 – Black happily exploits them.

Now, the blockade is lifted, and Black’s advantage disappears with it.