The Open System, Main Line is a variation of the French, Tarrasch Variation, catalogued as ECO C09. The line runs 1. e4 e6 2. d4 d5 3. Nd2 c5 4. exd5 exd5 5. Ngf3 Nc6 6. Bb5 Bd6 7. dxc5 Bxc5 8. O-O Ne7 9. c3, reaching the position shown below after 17 half-moves.
Black holds the centre with pawns on d5. Development is level at three minor pieces each. It is Black to move after nine moves. White has castled while Black’s king is still uncommitted; Black’s d-file pawn is isolated; the e-file file is fully open.
On the French, Tarrasch Variation generally: White plays 3.Nd2 instead of 3.Nc3, keeping the c-pawn free to advance. A flexible, positional approach to the French Defense.
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 6 French, Tarrasch Variation variations →
The Open System, Main Line goes 1. e4 e6 2. d4 d5 3. Nd2 c5 4. exd5 exd5 5. Ngf3 Nc6 6. Bb5 Bd6 7. dxc5 Bxc5 8. O-O Ne7 9. c3. It is a variation of the French, Tarrasch Variation and is catalogued as ECO C09.
The Open System, Main Line is ECO C09. ECO codes group openings by their move order, so nearby codes cover closely related lines of the French, Tarrasch Variation.
Stockfish evaluates the position after 1. e4 e6 2. d4 d5 3. Nd2 c5 4. exd5 exd5 5. Ngf3 Nc6 6. Bb5 Bd6 7. dxc5 Bxc5 8. O-O Ne7 9. c3 at +0.27 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.
Black holds the centre with pawns on d5. Development is level at three minor pieces each. It is Black to move. White has castled while Black’s king is still uncommitted; Black’s d-file pawn is isolated; the e-file file is fully open.