411 REFERENCE · Wikibooks
Chess Opening Theory/1. d4/1...d5/2. c4/2...c6/3. Nc3/3...Nf6/4. Nf3/4...e6/5. Bg5
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Semi-Slav defence Semi-Slav defence D43-D44
5. Bg5
This super-sharp move is often today a true gambit. White intends to offer the c-pawn as a real sacrifice. Here Black can try the solid 5...Nbd7, which leads into the Queen's Gambit Declined (Cambridge Springs Variation), the sharp Botvinnik Variation (5...dxc4 6. e4 b5 7. e5 h6 8. Bh4 g5 9. Nxg5! hxg5 10. Bxg5 with tremendous complications), or the even sharper Anti-Moscow variation, 5...h6 6. Bh4 dxc4 7. e4 g5 8. Bg3 b5.
Theory table
Botvinnik variation 5. ... dxc4 Moscow 5. ... h6 6. Bxf6 Anti-Moscow 5. ... ... 6. Bh4 Cambridge Springs 5. ... Nbd7
References
Semi-Slav Defence