A tactical slip in time trouble.
After 6.Nb5 Rd7 7.Bxe5 Rxe5 Black remains on top, but his strong knight is gone.

Black later realized his material advantage.

An unexpected advance that drastically alters the balance of the position.

1...b6 2.Ba4! White is soon able to land a knight on c6
1...cxb4 2.axb4 Bxb4? 3.Qxf6 Bxc3 4.Ng4 h5 5.Nh6+ Kh7 6.Bxg6+ with a decisive attack.

White has emerged with a mobile pawn majority on the queenside.

Weakening the a2-g8 diagonal, but it was not easy to find a constructive plan.

White later realized his material advantage.

This exchange sacrifice completely changes the logic of the position. Now the threat is 2 Bf4.

This lets the white knight occupy the newly created post on e5.

2...Nd7 3.Bxh6 Re8 was preferable, when 4.Bd3 Nb6 5.Ne5 Nxd5 6.Be4 keeps a clear initiative.