Leningrad Variation

The Leningrad Variation, 4. Bg5, answers Black's pin with one of White's own. It is named after the Leningrad players, Boris Spassky among them, who developed much of its theory. Once the f6-knight is pinned, it no longer exerts full control over e4 or d5, and the advance d5 becomes both the point of the move and its natural consequence. Play almost always runs 4...h6 5. Bh4 c5 6. d5 or 4...c5 5. d5 h6 6. Bh4. It is a fairly uncommon choice against the Nimzo-Indian. Engines rate the position as balanced, and online results are close to even.

After 4...h6 5. Bh4 c5 6. d5, the Benoni Defense line 6...d6 7. e3 Bxc3+ 8. bxc3 e5 gives Black a dark-square blockade resembling the Hübner Variation, except that White's dark-squared bishop stands outside the pawn chain. Black often breaks the pin with ...g5, which also restrains f2-f4, and because this loosens the kingside, the king frequently walks to c7 via d8 instead of castling. The Averbakh Gambit, 6...b5, attracted wide attention in the 1970s after Mikhail Tal defeated Spassky with it at Tallinn 1973.