Nimzo-Indian: Classical, 4...O-O 5.a3 6...b6 7.Bg5
Nimzo-Indian Defence — Classical Variation, 4…O-O 5.a3 Bxc3+ 6.Qxc3 b6 7.Bg5
Definition
This line is a sub-variation of the Nimzo-Indian Defence that takes shape after the sequence 1.d4 Nf6 2.c4 e6 3.Nc3 Bb4 4.Qc2 O-O 5.a3 Bxc3+ 6.Qxc3 b6 7.Bg5. It belongs to the Classical Variation, identified by White’s early 4.Qc2, which defends the knight on c3 and avoids doubled pawns. The particular move order given features:
- …O-O on move 4 — rapid king safety for Black.
- 5.a3 — immediately questioning the bishop on b4.
- …Bxc3+ — Black exchanges on c3, doubling White’s c-pawns yet gaining time to develop comfortably.
- …b6 — Black prepares a fianchetto of the queen’s bishop to b7, eyeing the e4-square and long diagonal.
- 7.Bg5 — White pins the f6-knight, hinders …d5, and keeps the bishop pair.
Strategic Themes
- Structure versus Bishop Pair
White accepts doubled c-pawns (c2–c3) in return for the two bishops and a central pawn majority (d- and e-pawns). Black strives to prove the pawns are weak by targeting c4 and c3. - Dark-Squared Control
…b6 and …Bb7 reinforce control of e4 and d5. If Black achieves …d5 without concessions, his bishops become very strong. - The Pin on f6
7.Bg5 restrains …d5. Black often replies …h6, …d6, or …Bb7 followed by …Nbd7, slowly untangling. - Minor-Piece Imbalances
With bishops versus bishop + knight, many endgames favor White if the position opens; Black prefers piece blockades and swift piece exchanges.
Typical Plans
- White
- Prepare the central break e2-e4 by supporting it with f2-f3 or Nf3–d2.
- Push c4-c5 to gain space and activate the dark-squared bishop.
- Use the g5-bishop to increase kingside pressure; occasionally Bxf6 doubles Black’s f-pawns.
- Black
- Complete development with …Bb7, …d6, …Nbd7, and only then strike with …e5 or …d5.
- Pressure the doubled pawns with …Ba6, …Nc6-a5-c4, or rooks on the c-file.
- Seek trades that reduce the power of White’s bishops.
Historical Notes
The Classical Variation (4.Qc2) was championed by Samuel Reshevsky in the 1940s and 1950s. The specific …b6 line became fashionable after Efim Geller used it successfully in the mid-1960s. Top grandmasters such as Anatoly Karpov and Viswanathan Anand have employed the setup, valuing its solidity and flexibility.
Illustrative Mini-Game
The following short fragment shows the main ideas from both sides:
Notable Games
- Geller – Polugaevsky, USSR Ch. 1966 — A textbook example of Black’s minority attack on the c-pawns.
- Karpov – Piket, Tilburg 1997 — Karpov demonstrates the power of the bishop pair by breaking with e4 and penetrating on the dark squares.
Interesting Facts
- Because the line often transposes to Hedgehog structures (pawns on a3, b6, d6, e6), it appeals to players who enjoy slow maneuvering.
- The move 7.Bg5 was once thought inferior to 7.e3, but modern engines reveal dynamic possibilities after 7…h6 8.Bh4 d6 9.e3.
- The ECO code for the position after 7.Bg5 is E34.
When to Choose This Line
Pick this variation if you enjoy:
- Balanced positions with long-term strategical battles.
- The tension of bishop-pair versus structural weakness.
- Flexible move orders that can transpose into Hedgehog, Queen’s Indian, or Catalan-like setups.
Further Study
Recommended resources include:
- “Mastering the Nimzo-Indian” by Igor Stohl.
- “Chess Explained: The Nimzo-Indian” by Reinaldo Vera — chapters on 4.Qc2 lines.
- Database search for modern games by Maxime Vachier-Lagrave, who often essays this system with both colors.