Nimzo-Indian Defense: St. Petersburg Variation (variation 4)

This opening is a solid and flexible defense for Black against White's central pawn push.

The St. Petersburg Variation is a popular choice for Black in the Nimzo-Indian Defense, aiming to fianchetto the bishop on b7 and create a solid pawn structure. By playing b6 and Bb7, Black prepares to challenge White's center and control key squares on the board. The development of the knight to f6 and the castle kingside allow Black to complete their development and prepare for the middlegame. White's setup with e3, Bd3, and Nf3 is a flexible approach, allowing for various pawn breaks and piece maneuvers. The tension in the center can lead to dynamic play, with both sides having chances for active piece play and pawn breaks. Overall, the St. Petersburg Variation offers Black a solid and strategic option in the Nimzo-Indian Defense, with opportunities for counterplay and a balanced position.