4...f5 seems preferable, preventing Ne4.

Since the plan of tripling the major pieces would leave the c4-pawn in danger, Karpov prefers to open a new front on the kingside.

Thanks to his strong passed pawn and more active pieces, White is better.

Getting rid of the bad bishop and reducing White's control over the light squares, in particular c4.

After 2.Bxb5?! axb5 the weak pawn on c2 and the entry square on c4 are more relevant factors than the doubled b-pawns.

This sacrifice is hardly any correct, but White was short of active plans.

The extra pawn will be decisive.

Intending Bh4-g3 to swap Black's good bishop and prevent the ...Nh5-f4 manoeuvre. The bishop transfer to g3 is indeed a common idea in this French structure.

Black prepares ...e6-e5 in order to get rid of the backward pawn on e6.