1...f6? 2.Qxa7+-

A clever tactical resource.

4...Qxe4 5.Bxe4 Nc4 6.Kf2 Kf8 7.Bd5 Nd6 8.e4+/-

This converts the e-pawn into a strong passed pawn.

6...Ne7 would be better.

With the strong plan of Bd5 and e4-e5. The game continued:

Followed by e4-e5 and White won without difficulties.

By handing over the open file White manages to push his kingside pawns.

Provoking Black's next move so that a later f4-f5 is effected with tempo.

This lets White continue his plan, eventually leading to a strong attack. Correct was:
6...Qd4! 7.Qxd4 Nxd4 8.Rd1 Ne6 with just a slightly inferior endgame.