Morphy v The Petrov (part four)

PAUL Morphy's fourth game against the Petrov came in 1859, and the start of the game has quite a modern feel to it.
Morphy - Wincenty Budzyński
Café de la Régence
Petrov Defence Classical Attack
1.e4 e5 2.Nf3 Nf6 3.Nxe5 d6 4.Nf3 Nxe4 5.d4 d5 6.Bd3 Be7 7.0-0 Nc6
Morphy had played this line as Black three times in his match the previous year against Johann Löwenthal.
8.c4 Be6
This was Morphy's choice on the two occasions Löwenthal played 8.c4. David Hooper in A Complete Defence To 1 P-K4: A Study of Petroff's Defence (Pergamon Press, 1967) calls it "not so bad as its reputation."

White to make his ninth move

*****
*****
*****
*****
*****
9.Qb3!?
Löwenthal played 9.cxd5 in both games. Morphy's move, which has apparently not been repeated in master play, is not mentioned by Hooper.
9...Na5?
Immediately he has to think for himself, Budzyński goes wrong. Stockfish10 and Komodo10 like 9...0-0, and if 10.Qxb7?!, then 10...Nb4 gives Black a good game.
10.Qa4+ c6?!
The retreat 10...Nc6 seems slightly better, but Black's loss of time must hurt him.
11.Re1
Preceding this move with 11.cxd5!?, as given by the engines, looks even stronger.
11...f5
The engines prefer to offer a pawn sac by 11...0-0!, the point being that 12.cxd5 cxd5 13.Bxe4 dxe4 14.Rxe4 Rc8 gives Black good compensation in the shape of the bishop-pair and better-coordinated development. But after 11...0-0!, they reckon White gets a slight edge with 12.Qc2 or 12.c5.
12.cxd5 Bxd5 13.Bd2!
Better than 13.b4 Nc4 14.b5 Nb6.
13...Nxd2 14.Nbxd2 b5 15.Qc2 g6 16.Rxe7+?
A miscalculation. White is much better after the simple 16.a4, which brings his final piece into play without, as in the game, sacrificing material.
16...Kxe7 17.Re1+ Kf7
Best, according to the engines, was the bold 17...Kf6!, which prevents White sacrificing further material. The engines reckon White would then have insufficient compensation for the exchange. 17...Kf6! also complies with the general rule that a king is safest when snug against its own pawns.
18.Bxf5! gxf5?
Black should have declined the bishop with 18...Re8 or 18...Kg7, in either case with an unclear position.
19.Qxf5+ Qf6
The engines prefer 19...Kg7, but White has a winning attack after 20.Qg4+ Kf8 21.Re5.
20.Ne5+ Kg7 21.Qg4+ Kh6 22.Re3 Bxg2
Desperate stuff, but Black cannot avoid a quick mate in any event.
23.Kxg2 Rhg8 24.Rh3+ 1-0