Indian: Mexican Defence, 3.Nf3 e6 4.a3

Indian: Mexican Defence

Definition

The Mexican Defence—more commonly called the Black Knights’ Tango—is an off-beat member of the Indian Defence family that begins with the moves:

1. d4 Nf6 2. c4 Nc6

Origin of the Name

The line was popularised in the 1920s by the Mexican grandmaster Carlos Torre Repetto, whose creative, “dancing” knight manoeuvres prompted later writers to compare the knights to tango dancers—hence “Black Knights’ Tango” and “Mexican Defence.”

How It Is Used in Chess

• Surprise Weapon – Because it is rarer than mainstream Queen’s Gambit or King’s Indian systems, it often catches 1.d4 players off guard.
• Flexible Pawn Structure – Black withholds the central pawn break …d5 or …e5, allowing transpositions to the Nimzo-Indian, Queen’s Gambit Declined, or even the King’s Indian Defence.
• Piece Activity – Both black knights occupy advanced squares (f6 & c6) early, eyeing e4 and d4, and can quickly jump to b4, g4, or e5.

Typical Strategic Ideas

1. Central Counterplay – Black often prepares …e5 (Budapest-style) or …d5 (Queen’s Gambit-style) to challenge White’s centre.
2. Queenside Expansion – Set-ups with …a6 and …b5 mirror the ideas of the Chigorin or Benoni, giving Black space on the queenside.
3. Piece Pressure – The knight on c6 can jump to b4 to harass White’s c2 or d3 squares, or to e5 to pressure c4 and d3.

Historical & Notable Games

• Torre – Yates, Moscow 1925 – One of the first high-level appearances; Torre used the defence to beat Frederick Yates in a sparkling miniature.
• Kasparov – Radjabov, Linares 2003 – A modern example where Radjabov held the World Champion using Tango ideas.

Illustrative Mini-Game

A concise encounter showing standard tactics:

Interesting Facts

• When the ECO code system was created, the line received its own classification: E20–E21.
• The Mexican Defence was considered “unsound” for decades until computer engines and modern praxis rehabilitated many of its lines.
• It is one of the few major openings named after a nationality rather than a player or place.

3. Nf3 e6 4. a3
(Main Line vs. the Mexican Defence)

Definition & Move-Order Context

After 1. d4 Nf6 2. c4 Nc6 3. Nf3 e6 4. a3, White chooses a restrained but flexible set-up. The early a3:

• Prevents …Bb4, avoiding doubled c-pawns or Nimzo-type pressure.
• Prepares the queenside expansion b2–b4, gaining space and challenging the knight on c6.
• Keeps the option of Nc3 without pin worries.

Strategic Significance

By blocking …Bb4 and discouraging …Bb4+ ideas, White adopts a “Samisch-style” clamp often seen in the King’s Indian. Meanwhile, Black must decide how to generate counterplay:

1. …d5 Set-ups – Transposing to Queen’s Gambit structures, but with the knight oddly placed on c6.
2. …g6 & …Bg7 – King’s Indian-like, accepting that the c6-knight may later reroute via e7-g6.
3. Immediate …b6 – Fianchettoing the bishop and eyeing e4, hoping the a3–b4 expansion weakens c4.

Typical Continuations

One frequently cited main line runs:

4…d5 5. e3 (solidifies the centre) 5…Be7 6. Nc3 O-O 7. Qc2 (overprotects e4, eyes h7) 7…a6 8. b4 dxc4 9. Bxc4 b5.

Here both sides have staked claim to the queenside; Black relies on pawn tension while White enjoys more space.

Model Game Reference

• Shirov – Korneev, Pamplona 1997 – White employed 4. a3 and scored a sharp attacking win after sacrificing a pawn on the queenside for central domination.

Example Position You Can Visualise

After 1. d4 Nf6 2. c4 Nc6 3. Nf3 e6 4. a3 d5 5. cxd5 exd5 6. Nc3 (diagram in your head) we reach:

• White pawns: a3, d4, e2, f2, g2, h2
• Black pawns: d5, e6, f7, g7, h7, plus the usual queenside pawns
• White pieces are primed for e2–e4; Black must decide whether to break with …Ne4 or …Bg4.

Practical Tips for Both Sides

• For White: Do not delay b2–b4 too long; otherwise the a-pawn can become a weakness rather than a lever.
• For Black: Consider the manoeuvre …Ne4 followed by …f5 to seize dark-square control if White plays passively.
• Endgames often favour White thanks to the queenside space advantage created by a3–b4.

Interesting Tidbits

• Some databases label 4. a3 the “Spanish Variation,” confusingly echoing the Ruy Lopez—illustrating how naming conventions in chess can overlap.
• Engine evaluations hover close to 0.00, yet practical results favour White, reflecting how uncomfortable Black can feel with an early Nc6 against stable Queen’s Gambit structures.