White's c5 in Semi-Slav (or Slav) Defense Lately, I've been experimenting as white with pushing the c pawn in the Semi-Slav Defence, but mostly in blitz games, so I would be very thankful if some of you could analyze a bit and point out if there are any major drawbacks compared to other moves, as longer games could look quite different.

[fen " w - - 0 1"]

1. d4 d5 2. c4 Nf6 3. Nc3 e6 4. Nf3 c6 5. Bg5 Nbd7 (5... Be7 6. e3 O-O 7. c5) 6. e3 Be7 (6... h6 7. Bf4 Be7 8. c5) 7. c5


My prerequisite for playing c5 is that I managed to get bishop out to g5/f4/g3 and pushed a King's Pawn to e3, while my opponent didn't push his bishop to b4 (so it's on f8/e7/d6).

In the next few moves I usually play Be2/Bd3 and O-O, and later on it depends on the opponent's response.

What usually happens afterwards is that my bishop is pushed to h2-b8 diagonal (if it wasn't already there), and if black goes for pawn-exchange on Queen's side (by e.g. (X)... b6 (Y). b4 bxc5 (Z). bxc5), I have a strong b-line due to my bishop preventing opponent's Rb8.

Some other players block out Queen side pawns and try to get my black-square Bishop for a Knight, but I feel like it still leaves me stronger.

Some examples of live games:

[fen "r1bqk2r/pp1nbppp/2p1pn2/3p2B1/2PP4/2N1PN2/PP3PPP/R2QKB1R w - - 0 1"]

7. c5 a5 8. a3 O-O 9. b4 b6 10. Be2 Ba6 11. O-O Bxe2 12. Qxe2 Re8 13. Bf4 Nh5 14. Be5 Nxe5 15. Nxe5 Nf6 16. Nxc6 Qc7 17. Nxe7+ Rxe7 18. Nb5 Qc6 19. Nd6 g6 20. Qf3 Kg7 21. Qg3 axb4 22. axb4 bxc5 23. b5 Ne4 24. Nxe4 Qc8 25. Qe5+ Kg8 26. Nf6+ 1-0


OK, my opponent made a clear mistake with 14... Nxe5, it seems like not playing this position very often is one of the reasons why it happens, as this was a Blitz game. But that's exactly why I'm asking, as you can't expect such mistakes that often in classic games.

Another example:

[fen " w - - 0 1"]

1. d4 d5 2. c4 c6 3. Nc3 Nf6 4. Nf3 Bg4 5. Bf4 e6 6. e3 Bd6 7. Be5 O-O 8. Be2 a6 9. c5 Be7 10. O-O a5 11. a3 b6 12. b4 bxc5 13. bxc5 Nbd7 14. Bg3 Ne4 15. Nxe4 dxe4 16. Ne5 Bxe2 17. Qxe2 Nxe5 18. Bxe5 f6 19. Bg3 Qd5 20. Rab1 Rab8 21. Bxb8 1-0


Again, the opponent made a blunder with 20... Rab8, but I think I was already in a considerably better position at that point.

[fen " w - - 0 1"]

1. d4 d5 2. c4 c6 3. Nc3 e6 4. Nf3 h6 5. Bf4 Bd6 6. Be5 Bxe5 7. Nxe5 Nd7 8. Nxd7 Bxd7 9. c5 Nf6 10. e3 a6 11. Bd3 b6 12. b4 a5 13. a3 axb4 14. axb4 Rxa1 15. Qxa1 b5 16. O-O O-O 17. Qa7 Qa8 18. Ra1 Qxa7 19. Rxa7 Rd8 20. f3 Kf8 21. Kf2


I made a mistake later on and ended up with one pawn less, but managed to get a draw. However, at this point of the game, I'm in a clearly better position.

[fen " w - - 0 1"]

1. d4 c6 2. c4 d5 3. Nc3 e6 4. Nf3 Nf6 5. Bg5 Be7 6. e3 O-O 7. c5 Nbd7 8. b4 Nh5 9. Bxe7 Qxe7 10. Be2 Nhf6 11. O-O e5 12. dxe5 Nxe5 13. Qd4 Nxf3+ 14. Bxf3 Be6 15. a4 a6 16. Rad1 Nd7 17. Bg4 Bxg4 18. Qxg4 Nf6 19. Qf4 Rae8 20. h3 Ne4 21. Nxe4 Qxe4 22. Rd4 Qc2 23. Rfd1 Qxa4 24. Qc7 Qb5 25. Rg4 Qe2 26. Rdd4 Rb8 27. Qe5 Qe1+ 28. Kh2 g6 29. Rh4 Qxf2 30. Qg5 Rbe8 31. Qh6 Qxg2+ 32. Kxg2 f5 33. Qxh7# 1-0


In this game, there were significant mistakes on both sides, but once again, it's Blitz so it happens.

What I want to know is, if you were black, would you be happy with me as white playing c5, and why (or why not)? I have troubles finding games with c5, so I guess there must be a reason why it isn't popular. But I know the move itself isn't that problematic (there are better moves perhaps, but a lot of popular openings are often played with suboptimal moves), so why is it so rarely played?
This is problem 34 from The Reassess Your Chess Workbook: How to Master Chess Imbalances by IM Silman. The notes are derived from his annotations:


  White has tried many moves here: 9. e4, gaining central space, and 9. b3, preparing to fianchetto the c1-Bishop and also giving White the chance to meet ...dxc4 with bxc4, both make sense. How would you judge the aggressive 9. c5?


[FEN ""]
[StartPly "16"]

1. Nf3 d5 2. d4 Nf6 3. c4 c6 4. Nc3 e6 5. e3 Nbd7 6. Qc2 Bd6 7. Bd3 O-O 8. O-O Qe7 9. c5 Bc7 10. e4 dxe4 11. Nxe4          


What does White achieve in the final position?


Better control over e4 and d6
Black's freeing maneuver of b6 and c5 has been stopped
Although d4 is a backward pawn, it cannot be attacked so easily and helps cramp Black


For why c5 is not as popular, Silman offers:


  At one time this move would have been the object of derision; White makes a one-move threat that's easily dealt with and... takes all the pressure off the Black d5-pawn.


In summary, c5 is played to gain space, hence cramping Black.