Slav: 3.Nc3 dxc4 4.e4 b5 5.a4

Definition

The sequence 1. d4 d5 2. c4 c6 3. Nc3 dxc4 4. e4 b5 5. a4 is a sharp and ambitious branch of the Slav Defense. After White’s provocative 4. e4, Black supports the extra c-pawn with 4…b5, and White instantly undermines that support by 5. a4. The opening is often called the “Slav Gambit” or “Alekhine–Sokolsky Variation.” Its defining characteristics are:

A temporary pawn sacrifice by White (the c4-pawn) to seize space in the center with e2–e4.
An immediate flank counter by Black (…b7–b5) to cling to the pawn.
White’s a-pawn thrust (a2–a4) to pry open the queenside and expose the b5-pawn as a tactical target.

Typical Move Order

1. d4 d5 2. c4 c6
3. Nc3 dxc4
4. e4 b5
5. a4

The most common continuations from here are:

5…b4 6. Na2 Nf6 7. Bxc4 e6 8. e5 Nd5 – Black keeps the extra pawn but lags in development, while White enjoys space and active pieces.
5…a6 6. axb5 cxb5 7. Nxb5 – White regains the pawn with a lead in development; the line is highly tactical.
5…e6 6. axb5 cxb5 7. Nxb5 – another attempt to consolidate that rarely succeeds because the b5-pawn is too loose.

Strategic Themes

Central Domination. By playing 4. e4, White erects a powerful pawn duo on d4/e4, cramping Black’s minor pieces.
Pawn Structure. Black’s …b5 pawn chain looks solid but is in fact fragile; its base (b5) can be attacked by a2–a4 or pieces on the a-file and long diagonal.
Development vs. Material. Black hangs onto the extra c-pawn at the cost of delaying kingside development; if Black fails to catch up, tactics favor White.
Queenside Files. After the a- and c-files open, rooks become powerful. White often doubles rooks on the a-file; Black counters by staking out central squares (e5, d5).

Historical Context

Although Alexander Alekhine tested the line during 1920s simultaneous exhibitions, it was Vsevolod Sokolsky and later Efim Geller who made it fashionable in serious tournament play after World War II. In modern times the variation has appeared in the repertoires of grandmasters such as Alexei Shirov and Anish Giri, particularly in rapid and blitz where surprise value is paramount.

Illustrative Game

The following miniature shows the danger Black faces when clinging too stubbornly to the pawn:

V. Sokolsky – D. Postnikov, USSR 1949: White’s central pawn roller and rapid development smashed through after Black’s ill-timed …c5 break.

Typical Plans

White
- Regain the pawn on c4 or b5 with tactical pressure.
- Exploit open a- and c-files with rooks.
- Push e4–e5 at the right moment to cramp Black’s knight and open the centre.
- Sometimes sacrifice another pawn (d4) for piece activity in the style of the King’s Gambit.
Black
- Finish development: …e6, …Nf6, …Bb4, and quick castling.
- Return the extra pawn at a convenient moment to liquidate pressure.
- Challenge the centre with …c5 or …e5 once pieces are out.
- Keep the queenside closed if possible with …a6/…b4, restricting White’s knight on c3.

Common Tactical Motifs

Na2–b4–d5 fork exploiting the advanced b-pawn.
Bxc4 sacrifice followed by Qf3 or Qh5+ targeting f7 if Black omits …e6.
Axle-pin on the a-file: Ra1–a3–h3 swing after the a-file is forced open.

Modern Evaluation

Computer engines rate the position after 5. a4 as roughly equal (≈0.20) but dynamically unbalanced. Over-the-board results slightly favor White in practice because precise defense is required to neutralize the initiative.

Interesting Facts

When Garry Kasparov first analysed the line for his 1993 PCA title defense, he remarked that “Black walks a tightrope on the queenside – one wrong step and the whole pawn chain collapses.”
The move 4. e4 shocked classical theorists because it violates the principle “don’t open the centre when behind in development.” Here White intentionally breaks that rule to create immediate tactical threats.
Many engines initially recommend 4…e5 instead of 4…b5, but that transposes to Grünfeld-like structures rather than a pure Slav.

Slav: 3.Nc3 dxc4 4.e4 b5 5.a4