Semi-Slav Defense: Accelerated Meran Variation
The Accelerated Meran of the Semi-Slav comes after 5.Nf3 a6, where Black plays the useful ...a6 before deciding on ...Nbd7. Black prepares ...dxc4 and ...b5 with extra support, while White looks for a setup that makes that pawn grab less attractive.
- Moves
- 1.d4 d5 2.c4 c6 3.Nc3 Nf6 4.e3 e6 5.Nf3 a6
- ECO
- D45
- Engine
- +0.27 · level (Stockfish 17.1, depth 20)
- Played
- 171 games in our lichess sample
- White scores
- 55.6%
Key ideas for both sides
White
- 6.b3 keeps a pawn ready to recapture on c4, so ...dxc4 no longer wins time against a bishop.
- After ...Bb4, Bd2 breaks the pin and Bd3 with Qc2 prepares an e4 push.
- If Black takes on c4, the c4-c5 clamp is no longer available, so aim for e4 and a central majority.
- Consider c5 yourself in some lines, gaining queenside space now that ...a6 has weakened b6.
Black
- Use ...a6 to support ...b5 after ...dxc4, so the pawn on c4 can be kept or traded on your terms.
- Against b3, switch plans with ...Bb4 and ...Nbd7 and castle, then look for ...c5 or ...e5.
- If White plays Be2 or Bd3, the engine line shows ...dxc4 followed by ...c5 and ...b5 in one go.
- Do not rush ...b5 before taking on c4; a pawn on b5 can be hit by cxb5 with a broken structure.
Plans and pawn structure
Black's pawn triangle on c6, d5 and e6 is solid, and ...a6 gives it a queenside extension. If White allows it, Black plays ...dxc4, ...b5 and ...c5 to free the c8 bishop toward b7. White's b3 setup stops that and leads to a slower game where Black castles and later pushes ...c5 or ...e5. White's main central plan is e4 after Bd3 and Qc2, after which an opening of the center favors the side with better development.
Where the engine's main line heads: Black's pawn triangle: c6, d5, e6. Black's triangle of pawns on c6, d5 and e6: very solid, but it can shut in the c8 bishop.
What the engine plays from here
Stockfish 17.1 at depth 20 rates the position +0.27: level. Its three top choices for White:
- +0.27 6.b3 Bb4 7.Bd2 Nbd7 8.Bd3 O-O
- +0.17 6.Bd2 Nbd7 7.Qc2 Be7 8.e4 dxe4
- +0.17 6.Be2 dxc4 7.Bxc4 c5 8.e4 b5
Pawns, from White's side.
How it scores on lichess
171 rated lichess games reached this position; White scored 55.6%.
Light: White wins. Grey: draws. Dark: Black wins. About the sample.
How to play against it
With White, 6.b3 is the simplest way to blunt ...a6: c4 stays defended by a pawn. Follow with Bd2, Bd3 and Qc2, castle and prepare e4. Avoid playing Bd3 too early if Black can take on c4 and push ...b5 with gain of time.
Questions
What are the moves of the Semi-Slav Defense: Accelerated Meran Variation?
The Semi-Slav Defense: Accelerated Meran Variation starts 1.d4 d5 2.c4 c6 3.Nc3 Nf6 4.e3 e6 5.Nf3 a6. Its ECO code is D45.
Is the Semi-Slav Defense: Accelerated Meran Variation good for Black?
Stockfish 17.1 rates the position +0.27 at depth 20, which is level. A flexible choice for Black players who know Meran ideas well, while White can keep things simple with a b3 setup and steady development.
What is the main idea of the Semi-Slav Defense: Accelerated Meran Variation?
Black spends a move on ...a6 to make the ...dxc4 and ...b5 plan stronger. White's best answer is often b3, keeping c4 protected by a pawn and leading to a quieter fight about the e4 and c5 breaks.
What should White play next?
The engine's first choice is b3, with Bd2 and Be2 close behind. 6.b3 supports c4 with a pawn so that ...dxc4 no longer gains a tempo on a bishop.
Related lines
Updated October 2026. Sources and method.