Critical Move #2

In today's game in the FIDE World Cup, Gata Kamsky sacrificed a piece for an attack, can you see the piece sacrifice in this position?

White's position wasn't so interesting till now and positionally it was getting worse, but Kamsky found a way to take initiative ...

It worth to note that in this game, similar to Critical Move #1, the side with the extra piece failed to find the best move, in the case of Aronian drawing and here Mamedyarov losing.