3...h6 4.Bh4 g5: the h-file opens is variation 3 of 6 in the Torre Attack course, a intermediate opening course for White (ECO A46). It runs 21 moves and begins 1. d4 Nf6 2. Nf3 e6 3. Bg5 h6 4. Bh4 g5 …. Black chases the bishop with the h- and g-pawns. White drops it back to g3 and lets Black take it. The h-file opens and White builds a strong centre with c3 and e4. In the lesson every move is explained on a board and then drilled; it is free.
Move by move
1. d4 – White takes space in the centre and frees the c1 bishop.
1... Nf6 – Black develops and stops White from playing e4 at once.
2. Nf3 – The Torre move order. White develops first and keeps every plan open.
2... e6 – Black opens the f8 bishop.
3. Bg5 – The bishop pins the f6 knight.
3... h6 – Black asks the bishop at once.
4. Bh4 – The bishop keeps the pin.
4... g5 – Black chases the bishop. It gains space, but it weakens the kingside.
5. Bg3 – The bishop drops back and keeps aiming at c7.
5... Ne4 – Black attacks the bishop again.
6. Nbd2 – White develops and lets Black take the bishop. Then the h-file opens.
6... Nxg3 – Black takes the bishop and gets the bishop pair.
7. hxg3 – White takes back with the h-pawn. The h-file opens for the rook on h1.
7... Bg7 – Black puts the bishop on the long diagonal to hit d4.
8. c3 – White guards d4 and blunts the g7 bishop.
8... d6 – Black controls e5.
The lesson goes on for 5 more moves, each with its explanation.