About this opening
Queen's Gambit Declined: Semi-Tarrasch Defense, San Sebastian Variation is an opening in the Encyclopedia of Chess Openings,
classified under code D41. ECO group D (D00–D99)
covers closed games and semi-closed games beginning 1.d4 d5, covering the Queen's Gambit, Slav, Grünfeld and related queen-pawn structures. This particular variation is reached
after 18 half-moves from the
starting position, with the move sequence 1. d4 d5 2. c4 e6 3. Nc3 Nf6 4. cxd5 Nxd5 5. e4 Nxc3 6. bxc3 c5 7. Nf3 cxd4 8. cxd4 Bb4+ 9. Bd2 Qa5.
It belongs to the Queen's Gambit Declined family.
Within that family this is a level-2 branch (the Semi-Tarrasch Defense → San Sebastian Variation line). The immediate parent line is Queen's Gambit Declined: Semi-Tarrasch Defense, transitioned via 9…Qa5.
The opening sequence in prose form: 1.d4 d5, 2.c4 e6, 3.Nc3 Nf6, 4.cxd5 Nxd5, 5.e4 Nxc3, 6.bxc3 c5. From this position the encyclopaedia records no further canonical continuations — practical play branches into unnamed transpositions or returns to the parent line for alternative ideas.
Use the interactive board above to walk through the moves position-by-position. Click any move in the navigation to step backwards, or use the keyboard arrow keys. For statistical data — how often master-level players have reached this position, White's win-rate, draw frequency, Black's score — see the panel in the right column.
Caissly's coverage of D41 extends through every named sub-variation in this line and across all four locales (English, Spanish, Portuguese, Russian). Where editorial commentary exists for a specific variation it appears as the page body; otherwise the page presents the structural data, board, and statistics as shown here.