Nimzo-Indian Defense: Samisch-Keres Variation
Nimzo-Indian Defense, Sämisch – Keres Variation
Definition & Move-order
The Nimzo-Indian Defense, Sämisch – Keres Variation is a sharp sub-line of the Nimzo-Indian that arises after the following moves:
1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. a3 c5 5. d5 b5
White’s fourth move, 4.a3, defines the Sämisch Variation, in which White immediately questions the fianchetto bishop. Black’s fifth move, 5…b5, was popularized by the legendary Estonian grandmaster Paul Keres and gives this line its second name. The ECO codes E23–E24 are usually assigned to the Keres Variation.
Strategic Ideas
- Counter-attacking on the flanks: Instead of passively retreating the bishop, Black challenges White’s center by striking on the queenside with …c5 and …b5, aiming for rapid piece activity.
- Imbalanced pawn structure: After 6. dxe6 or 6. e4 (common continuations), asymmetrical pawn islands arise, offering both sides long-term winning chances.
- Bishop pair versus structure: White usually gains the bishop pair when Black exchanges on c3, but at the cost of doubled c-pawns and a potentially weak light-square complex around d4–c3.
- Timing of …exd5: Black can postpone or immediately capture on d5, each leading to distinct middlegame plans (…bxc4 ideas, or quick …d6 & …e5 breaks).
Typical Continuations
- 6. dxe6
6… fxe6 7. cxb5 d5 8. Nf3 (sharp race between development and pawn targets) - 6. e4
6… Nxe4 7. Qg4 Nxc3 8. Qxg7 Ne4+ 9. axb4 Qf6 (tactical storm; both kings unsafe) - 6. cxb5
6… exd5 7. axb4 d4 8. bxc5 dxc3 9. Qxd8+ Kxd8 (material imbalance with exposed king but strong minor pieces for Black)
Historical Significance
Paul Keres introduced 5…b5 in the mid-1940s as a dynamic antidote to the then-fashionable Sämisch. His games against Romanovsky and Boleslavsky demonstrated that Black could take the initiative on the queenside without fearing the doubled-pawns weakness traditional in the Nimzo-Indian.
The line hasn’t reached the absolute top tier of modern elite practice, largely because precise computer-assisted preparation is needed, but it remains a potent surprise weapon—especially in rapid and blitz time controls where concrete calculation outweighs long-term positional subtleties.
Illustrative Mini-Game
The above 20-move slugfest (modelled on a Keres analysis game) shows the main motifs: Black sacrifices the b-pawn, opens files for his pieces, and hounds White’s queen while lagging behind in development only temporarily.
Modern Usage
Grandmasters such as Alexander Morozevich, Richard Rapport and Daniil Dubov have occasionally revisited the Keres Variation to catch opponents off-guard. In practical play, it often appeals to players who enjoy:
- Unbalanced structures from an early stage.
- Tactical, calculation-heavy middlegames.
- The psychological advantage of leaving “booked-up” opponents on their own early.
Interesting Facts & Anecdotes
- The move 5…b5 was once annotated by Keres as “the principle of counter-attack in its purest form”—a philosophy he championed throughout his career.
- Modern engines fluctuate wildly in their evaluation of the line: at depth 20 the position may show +0.80 for White, only to flip to –0.25 at depth 40 as tactical resources emerge for Black.
- Because the variation forces early confrontations, it is a popular choice in correspondence chess, where deep home preparation neutralizes much of White’s theoretical edge.
- Despite being played only sporadically, it has generated a disproportionate number of Game of the Week prizes in online leagues due to its fireworks-laden nature.
Key Takeaways
The Nimzo-Indian Defense, Sämisch – Keres Variation is an enterprising way for Black to sidestep more positional branches of the Nimzo. By immediately challenging White’s center with …c5 and …b5, Black gambles structural soundness for piece activity and tactical chances—an approach entirely in the spirit of its creator, Paul Keres.