In order to exploit the new weakness on a5.

White later realized his positional advantage.

Softening up White's pawn majority and freeing the d5-square for the knight.

Preventing ...b5-b4, but also leaving the queenside structure in a bad shape.

3.Ne5 would be better.

After some consolidating moves Black is ready to fight for the initiative by ...Nbd5 or ...Nc4.

This loses a piece.

10.Nf3 Rc4! Trapping the queen.

Black soon won.

Softening up the d5-square for the knight.