Figure[Black to move]

What checks does Black have with his bishop? BxN+. The move also attacks a pawn at b4, and a protected one at that; and the pawn guards the square anyway, along with the White rook. So there is nothing here yet, but if you at least see this much you will have the idea in hand and can use standard techniques to build a little combination out of it. Black takes the pawn with another piece: 1. …Rxb4; and now if 2. RxR, Black plays BxN+ and wins back the rook with the gain of a piece and a pawn. (In the actual game White replied 2. Ra5, BxN+; 3. RxB; Rf4+ (another double attack, this time against White's king and f-pawn); 4. Ke3, Rxf5 and Black was two pawns ahead.)