Originally posted by Data FlyThanks.I've often wondered about c4 but not had the confidence to play it as all the theory I've seen seems to advocate putting pressure on the white d pawn, or even taking it.
Both! Don't even think about castling kingside - you''ll walk into Bxh7 tricks. Leave the king where it is and play c5, Nc6, Qb6 and then f6. One plan for Black is to deliberately block up the queenside with c4 (preferably after b4 by White) and then castle queenside.
 Here's an example by Petrosian. Funnily enough he doesn't play f6 in this game: ...[text shortened]... Be3 Nb6 28. Bf1 Qg6 29. f4 Rc8 30. Qd2 Rc2 31. Bd3 Rxd2
32. Bxg6 fxg6 33. Bxd2 gxh5 0-1