Once again, prophylactic thinking needs to be applied in order to find the best move here for White. What does Black want to play? ...e4!, restricting the white knights and opening a dangerous diagonal for the c7-bishop.

1.Bxc8! Raxc8 2.e4! +/-

Just in time! White will be the owner of all the light squares (f5, d5, c4) and is looking at a scenario where the knight is much better than the bishop.

The position is around equal, but can you find a plan to take advantage of a weak square?

We have seen this maneuver in another one of Botvinnik's games. He wants to support a knight jump to c6 in the future. In case Black trades on b4, White would win another tasty square on b4 for a knight.

Petrosian kicks the knight on e5 but on the other hand, his bishop on g7 will be restricted and some weakness will be created as well.

Nb4-Nc6 or Bc3-Bb4 are some interesting plans here for White.

4...Bf7! was better!

Bb4 is the threat winning a piece.

Bb4 is coming and d5 will suffer.