removing all threats and freeing the Be6.
The end of the game probably took place amidst time-trouble, and there followed instead 38...Be5+? 39.Kg2 (White wins with 39.Kh4!! Qe8 40.Bc6) 39...Bxd5+ 40.Rxd5 Qb7? (with mutually correct play, after 40...Qe6 41.Rxe5 Qxe5 42.Nxh6+ Kg7 43.Nf5+ Kh8 44.Qf2 Qd5+ 45.Kh2 Rf7 46.Qf4 Rh7+ 47.Kg3 Ne4+ 48.Kg2 Ng5+ 49.Kg3, a draw could result) 41.Ne3, and White won.

Black has a decisive attack.

The black king is in an exceptionally dangerous position, under the fire of the white pieces. The white knight attacks numerous important squares, his queen is ready to penetrate to the eighth rank, he has pressure on the f-file, and the epawn can advance. However, immediate checks or direct attacks lead to nothing. Unfortunately, in the event of the bishop taking the knight on f6, the black queen recaptures with check. Reasoning along these lines, one can appreciate that the white king is poorly placed on b2, and there is a square where he would not be subject to checks:

White’s attack comes to a dead end after 35.Ne6+ Kg8 36.Qb8+ Qe8.
Another false trail is the tempting 35.Re6 Qf5 36.Qxf5 Nxf5 37.Bxf6, because of 37...h6!.
All of Black’s pieces are tied to the defence of something or other, and the only move that does not lose at once is to move out of one pin into another.

However, in this case, the winning path for White is already not so difficult:

The rook joins in the attack with decisive effect.

On 39...Nf6, the most effective move is 40.Nf8.

With play on both flanks. The rook easily outplays the knight, and White wins.

Whatever aggressive move Black makes in the centre, his king will come under a dangerous check. Moreover, if we transfer the move to White, it becomes clear that solving the problem of his own king in the centre will require more than one tempo. This means that it is the ideal time for some useful prophylaxis:

He also loses after 20.Nc5 Bxc5 21.Rxc5 g5 22.Bd2 d5! 23.Qe3 Rhf8, with the threats of 24...Rf5 and 24...Qxh2.

A) 21.Qc2 g5 22.Qxc6+ Bb7 – This is one of the variations where the move 19...Kb7-a8! tells;
B) 21.Qg2 Rxe5+ 22.Bxe5 Bb4+ 23.Kf2 Qxe5 24.Kg1 Rf8 25.Kh2 Qe3–+.