A double exchange sacrifice!

Black's attack is unstoppable. White soon lost.

The missing fianchetto bishop is an invitation: ladies first!
15…Qd7!

17.b4, to drive the active bishop away, seems better.

Now Black is clearly pressing – pair of bishops, centralized rooks, and the black queen dominatingly present on White’s weakened kingside.

The most elegant way to escape from under the pressure.

The young American continues in style, but the simpler 18…Rd6 was also sufficient.

19…f5 should have been played.