After 2.f3?! Be6 a weak square appears on e3, and the fianchettoed bishop becomes severely restricted.

The exchange on d4 has yielded Black a semi-open file and reduced White's dynamic potential.

The active 5.e4 was preferable, e.g. 5...dxe3 6.Nfxe3 Nxe3 7.fxe3 Rcd8 8.Ra3 with just a slight disadvantage – Botvinnik.

Black starts working towards the target on e2.

, followed by ...Qe7, yields Black a clear advantage – Botvinnik.

Provoking e3-e4 in order to soften up the f4-square.

5.Bxf6 gxf6 6.Kh1 Ng6 7.Rg1 Kh7 with a slight advantage – Sax.

Black starts working on the f4 weakness.

Heading for g5 or h4, with an initiative.