Having extra material, it is better to defend the ‘base’ pawn, to win the game without undue adventures.

In the pawn endgame after 37...Rc4 38.Rxc4 dxc4 39.Kf1, the king is in the square, and the passed a-pawn brings White victory.

Black’s bishop on g5 is hanging, as is White’s Re4. But the black king turns out to be surrounded by white pieces when it takes on e4.

And now the key move of the variation:

Black resigned, because there is a threat of 32.Bd2#, and on 31...e4 there follows 32.Nh3#.

Black has an extra piece, but the pawn on a7 is very dangerous, and is impossible to capture with checks. For example, after 53...Qc1+ 54.Kh2! Nf1+ (54...Qb2+ 55.Qg2!) 55.Kg2 Ne3+ 56.Kf2 Qd2+ 57.Kg1 Qe1+ 58.Kh2 Nf1+ 59.Kg2 Ne3+ 60.Kh2 Qd2+ 61.Kg1 Qc1+ 62.Kf2 Qd2+ 63.Kg1, the game ends in a draw.

54.Kh1 Qe1+ 55.Kg2 Qg1#.

The white king has no protection, and Black obtains a winning queen endgame.

With a winning position.