1.d4 d5 2.c4 e6 3.Nc3 Nf6 4.Nf3 c5 5.cxd5 Nxd5 6.e3 Nc6 7.Bd3 opens the Semi-Tarrasch Defence: 1.d4 d5 2.c4... 7.Bd3, ECO D42. Lichess records 19,814 games in this line, which gives us a reliable view of how it actually performs in practice.
History and Notable Players
It arises from the Semi-Tarrasch Defence: 1.d4 d5 2.c4... 5.cxd5. Among the most prolific White practitioners are Yuri L Averbakh (8 games), Lajos Portisch (7 games), Wolfgang Uhlmann (7 games). Black-side regulars include Ludek Pachman (14 games), Ivan Farago (11 games), Arthur Bernard Bisguier (8 games).
Move Diversity and Theory Depth
Move choice is far from uniform in the Semi-Tarrasch Defence: 1.d4 d5 2.c4... 7.Bd3. At 1200 Elo, the top reply is cxd4, played 38.6% of the time. There are 3 other moves seeing meaningful share, and 71.6% of games stick to established theory. Entropy: 2.75. By 2500, Be7 dominates at 55.6% of replies; only 2 viable alternatives remain and 98% of moves are theory. Entropy drops to 1.30. That entropy collapse is the signature of a line where preparation pays off: at the top, players know the best move and play it.
Common Mistakes
- Drifting away from main theory — At 400 Elo, theory adherence sits at 55.6% — versus 91.5% at 2000. The most popular deviation is Nxc3 (played 22.2% of the time at 400, much less so up top). It looks fine but quietly hands the better-prepared side an edge.
- Neglecting development — It can feel productive to make extra pawn moves early, but falling behind in piece development is what loses most amateur games — especially in open positions where active pieces find squares fast.
- Playing without a plan — Each Semi-Tarrasch Defence: 1.d4 d5 2.c4... 7.Bd3 middlegame demands a specific approach. Decide whether the position calls for attack, manoeuvre, or simplification before reaching for a move.
Practice on Chessiverse
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