Chess Opening Theory/1. d4/1...Nf6/2. c4/2...e6/3. Nc3/3...Bb4/4. Bg5/4...h6

Nimzo-Indian Defence rd nd bd qd kd rd pd pd pd pd pd pd pd nd pd bl bd pl pl nl pl pl pl pl pl pl rl ql kl bl nl rl Nimzo-Indian Defence, Leningrad Variation 4...h6 Black drives the bishop back, so as to gain the ability to play ...g5 and break the pin at a later time. 5. Bxf6 Bxc3 6. bxc3 Qxf6 gives up the bishop pair and lessens White's ability to defend the weak c pawns, especially once they become fixed in place with ...c5, so the only good move is 5. Bh4. Nimzo-Indian Defence