QGA: 4.e3 e6 5.Bxc4 a6 6.O-O

QGA: 4.e3 e6 5.Bxc4 a6 6.O-O

Definition

This sequence of moves arises in the Queen’s Gambit Accepted (QGA) and is coded in modern opening reference works as ECO D24. After 1.d4 d5 2.c4 dxc4 3.e3 e6 4.Bxc4 a6 5.O-O, White has recovered the temporarily sacrificed c-pawn with the bishop, while Black has inserted the move …a6 before deciding how to complete development. The line is sometimes called the “Central Variation with …a6” or, in older literature, the “Alekhine–Janowski System.”

Move Order & Position After 6.O-O

The critical path is:

• 1. d4 d5
• 2. c4 dxc4  – the Queen’s Gambit Accepted
• 3. e3 e6  – White prepares to recapture; Black keeps the extra pawn for the moment
• 4. Bxc4 a6  – White regains the pawn; Black prevents Nb5 and prepares …b5
• 5. O-O  – White castles, reaching the tabiya that this definition concerns

Strategic Ideas

For Black:

• …b5 expansion. The pawn on a6 supports an immediate …b5, chasing the c4-bishop and claiming queenside space.
• Delayed …c5. After …b5 and …Bb7, Black often follows with …c5 to strike the d- and e-files, seeking full central equality.
• Minor-piece harmony. Black may route the g8-knight to d7 rather than f6 to avoid tactics on e6 and to support …c5.

For White:

• Rapid development. White is a tempo ahead of the main line 3.Nf3 variations and can aim for e4 in one go.
• Bishop pair leverage. The bishop on c4 eyes f7; if Black plays …b5 too early, Bxb5+ can be annoying.
• Central majority. After exchanges, the potential pawn duo e3–d4 can advance to e4–d5 for space or kingside play.

Typical Continuations

1. 6…Nf6 7.Qe2 c5 8.Rd1 b5 9.Bb3 Bb7 – the flexible “Korchnoi set-up,” balancing development and queenside expansion.
2. 6…c5 7.dxc5 Qxd1 8.Rxd1 Bxc5 – leading to an endgame in which Black’s structure is solid but passive.
3. 6…b5 7.Bd3 Bb7 8.a4 c6 – an ambitious attempt for space that risks the a- and c-files if mishandled.

Historical & Theoretical Significance

The move …a6 was popularised by Alexander Alekhine in the 1920s as a way to keep the extra pawn as long as possible. In the 1970s and 1980s Viktor Korchnoi revived the idea with modern, concrete analysis, demonstrating that Black could equalise or even outplay unprepared opponents. The line remains a staple in the repertoires of pragmatic defenders seeking clear plans without excessive memorisation.

Illustrative Games

• Korchnoi – Hübner, Candidates 1980
  The classic model game for Black’s 6…Nf6 plan. Korchnoi, as White, pressed but Hübner’s queenside expansion held firm and the game was eventually drawn.
• Anand – Kramnik, Dos Hermanas 1995
  Kramnik uncorked the immediate 6…b5 and, after precise play, achieved comfortable equality, showcasing modern move-order nuances.
• Kasparov – Shirov, Linares 1993
  A sharp version where Black delayed …Nf6, allowing Kasparov to sacrifice a pawn for initiative; ultimately Shirov’s accurate defence earned him half a point.

Interesting Facts & Anecdotes

• Alekhine reputedly discovered the idea of …a6 while analysing a simultaneous exhibition loss; he noted that preventing Nb5 would have saved him tactical grief.
• The variation has been a favourite of correspondence players because computer engines initially underestimated Black’s counterplay after …b5, giving humans a theoretical edge.
• Modern engines now consider the position after 6.O-O roughly equal (≈0.00), yet the line still scores above 55 % for White below 2200 FIDE, demonstrating the importance of understanding plans over raw evaluation.

When to Choose This Line

Opt for 4…a6 as Black if you:

• Enjoy solid but flexible structures with clear pawn breaks.
• Prefer to avoid the heavy theory of 3.Nf3 or 3.e4 QGA branches.
• Are comfortable defending slightly cramped positions in the early middlegame in exchange for straightforward plans.

Play 6.O-O as White if you:

• Want to keep the position fluid, reserving the choice between Qe2, Nc3, or a quick e4.
• Trust your middlegame skills to exploit the latent energy of the bishop pair against Black’s queenside pawns.

Further Study

Recommended resources include:

• “The Queen’s Gambit Accepted” by Evgeny Sveshnikov – detailed coverage of the …a6 systems.
• ChessBase Magazine opening surveys by Viktor Korchnoi (issues 56–60) – a first-hand master class.
• QGA overview to see how this branch fits into the larger family of Queen’s Gambit lines.