Slav: Chameleon, 5.e3 b5

Slav Defense: Chameleon Variation (5.e3 b5)

Definition

The Chameleon Variation of the Slav Defense arises after the moves 1. d4 d5 2. c4 c6 3. Nf3 Nf6 4. Nc3 a6 5. e3 b5. It is also widely known as the Chebanenko Slav, named after Moldovan trainer GM Vitaly Chebanenko. The position is reached when Black follows the preparatory pawn thrust …a6 with the immediate …b5, grabbing queenside space while keeping the central structure flexible—hence the nickname “Chameleon,” a system that can transpose into a variety of other Slav and Queen’s Gambit structures.

Typical Move Order

The critical path to the tabiya is:

1. 1. d4 d5
2. 2. c4 c6  – the Slav Defense
3. 3. Nf3 Nf6
4. 4. Nc3 a6  – the key Chebanenko move, restraining Nb5 and preparing …b5
5. 5. e3 b5  – the defining thrust of the Chameleon Variation

Strategic Themes

• Queenside space gain: The pawn duo on a6–b5 gives Black extra room on the queenside and keeps White’s minor pieces at bay.
• Flexibility: Black can adopt several set-ups:
  • …Bf5 or …Bg4 followed by …e6 for a Classical Slav feel;
  • …dxc4 and a later …c5 for Meran-like play;
  • …g6 and …Bg7 transposing to Slav–Grünfeld hybrids.
• Delayed commitment: By not putting the light-squared bishop on c8 immediately, Black waits to see where White’s pawns and pieces go before choosing the optimal development square.
• Typical pawn breaks: …c5, …e5, or …dxc4 followed by …c5 are the main thematic levers in the middlegame.
• Counter-play balance: White often reacts with 6.b3, 6.c5, 6.a4, or 6.cxd5, each trying to dent Black’s queenside structure or seize space in the center.

Historical & Practical Significance

The line became popular in the late 1990s when Moldovan and Russian grandmasters such as Viktor Bologan and Viorel Iordachescu began scoring notable wins. World-class players—Magnus Carlsen, Alexander Morozevich, Veselin Topalov, and Shakhriyar Mamedyarov—have since incorporated it into their repertoires, appreciating its richness of ideas and low maintenance compared with mainline Slavs.

Illustrative Game

Below is a model miniature showing the typical themes of harmonious development and timely …c5 break. Play through and observe how the “chameleon” adjusts to White’s set-up.

[[Pgn| d4 d5 c4 c6 Nf3 Nf6 Nc3 a6 e3 b5 b3 Bf5 Be2 e6 O-O Nbd7 Bb2 Be7 Rc1 O-O Ne5 Nxe5 dxe5 Nd7 cxd5 cxd5 Bd3 Bxd3 Qxd3 Rc8 |arrows|a6a5 b5b4 c6c5|squares|b5,c5]]

Typical Continuations After 5…b5

• 6.b3 (Main Line)

  This quiet move prepares Bb2, reinforcing the center. Black replies flexibly with …Bf5, …e6 and possibly …Nbd7, aiming for …c5 at a favorable moment.

• 6.c5

  Gains space and clamps …c5, but concedes d5 as a potential outpost. Black often reroutes a knight via d7-f8-g6 and later challenges the pawn chain with …e5 or breaks with …b4.

• 6.a4

  Immediately questions the b5-pawn. Black may respond with 6…b4 7.Na2 and decide between expanding on the queenside or striking in the center with …c5.

• 6.cxd5

  Attempts to open the center before Black is ready. After 6…cxd5 7.Bd3, the game often transposes to Exchange-Slav structures but with the extra flavor of …a6-b5 giving Black fresh possibilities.

Interesting Facts & Anecdotes

• The “Chameleon” moniker was popularized by GM Nick de Firmian in Modern Chess Openings because Black can shift between numerous pawn structures—much like a chameleon changes color.
• Magnus Carlsen first wheeled it out in top-level play at age 15 in Morelia/Linares 2006 against Veselin Topalov, holding comfortably with Black.
• GM Viktor Bologan authored an entire repertoire book around the system, calling it “the Slav that makes opponents think on their own from the very beginning.”
• Because …a6 is useful in many Slav-type positions, players who specialize in the line seldom fear sharp theoretical novelties; much of the battle takes place in the middlegame.

When to Choose the Chameleon Slav

• You enjoy flexible setups that can transpose into numerous pawn structures.
• You prefer positional maneuvering with occasional bursts of tactical play rather than heavy early-move theory.
• You want a solid but dynamic answer to 1.d4 without memorizing the massive body of mainline Slav/Meran theory.

Further Study

Review recent games by Magnus Carlsen, bologanv, and mamedyarov—all frequent practitioners. Pay special attention to how they time the breaks …c5 and …e5, and how they recycle the light-squared bishop between f5, g6, and occasionally h7.