White solves his main task at this moment, organising a blockade on c4, for which purpose his queen retreats to b3.

White has been ready for a queen exchange for some 20-23 moves, ever since he finished the march of his rook’s pawn! Black had to keep the queens on, choosing, for example, 33...Qg4 – White would face greater technical problems there.

Black resigned.

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.