The Main Line is a variation of the Semi-Slav Defense, catalogued as ECO D46. The line runs 1. d4 d5 2. c4 c6 3. Nc3 Nf6 4. e3 e6 5. Nf3 Nbd7 6. Bd3, reaching the position shown below after 11 half-moves.
Both sides have pawns in the centre (White on d4, Black on d5), and one pawn capture is available, so the structure has not settled yet. Development is level at three minor pieces each. It is Black to move after six moves.
On the Semi-Slav Defense generally: A complex defense combining ideas from the Slav and Queen's Gambit Declined.
You can play through this variation move by move in your browser — Learn mode walks the line with an explanation at each step, and Drill mode replays it from memory so you find out whether you actually know it. No account is required.
See all 63 Semi-Slav Defense variations →
The Main Line goes 1. d4 d5 2. c4 c6 3. Nc3 Nf6 4. e3 e6 5. Nf3 Nbd7 6. Bd3. It is a variation of the Semi-Slav Defense and is catalogued as ECO D46.
The Main Line is ECO D46. ECO codes group openings by their move order, so nearby codes cover closely related lines of the Semi-Slav Defense.
Stockfish evaluates the position after 1. d4 d5 2. c4 c6 3. Nc3 Nf6 4. e3 e6 5. Nf3 Nbd7 6. Bd3 at +0.38 at depth 18, which is a slight pull for White, within normal opening margins. Engine evaluation is only a starting point — at club level the practical value of a line is mostly about whether you know its plans better than your opponent does.
Both sides have pawns in the centre (White on d4, Black on d5), and one pawn capture is available, so the structure has not settled yet. Development is level at three minor pieces each. It is Black to move.