This week’s example sees an impressive grind against the master of such things, Anatoly Karpov. White emerges from the opening with the better endgame, thanks to the weakness on d5. Gelfand’s note to move 23 reads “White needs to create a second weakness, as in Nimzowitsch’s book”. The plan behind 23.a4 is to advance the pawn to a5 and fix a6 as the second weakness. This duly happens, and after a long grind, the combined effect of the two weaknesses eventually sees the black defences collapse.