Creating a protected square on d6, which can be exploited by the knight via d2-c4-d6, or even by the rook.

The desired 1...f5 permits 2.exf5! exf5 3.Rd6! with strong pressure; e.g. 3...f4 4.Bd3+! Kh8 5.Bg6+-

After 6...Rb8 7.Nab6 Nf4 8.Nxc8 Rfxc8 9.Nd6 White is also better, but at least material remains even.

White won without any problems.

Redirecting the idle knight to h6, where it will be helpful in exploiting in the complex of weak squares on g4, f5 and e4.

Challenging the main defender of the e4-square.

After 5.Bxf5 Nhxf5 , followed by ...Ne4+, White also has a hard time.

After seizing the centre Black starts a flank attack.

A tactical oversight. White should have accepted long-term inferiority after 7.fxg5 fxg5 8.hxg5 Nxg5.

Black wins material, and soon the game as well.