Key ideas
- 6...d6 stops Nd6+. The main line continues 7.Bg5 a6 8.Na3 b5, when the knight on a3 is offside and White's task is to bring it back into play while fighting for d5.
- After 9.Bxf6 gxf6 10.Nd5, White wins the d5 square but Black gets the bishop pair, the half-open g-file and the ...f5 break. Black chooses between 10...f5 at once and the Novosibirsk, 10...Bg7.
- 9.Nd5, the Chelyabinsk line, keeps the bishops on. After 9...Be7 10.Bxf6 Bxf6 11.c3 play is slower: White reroutes the a3 knight via c2 to e3 and both sides manoeuvre around d5.
- 7.Nd5 Nxd5 8.exd5 is the main positional alternative. The d5 pawn locks the centre, Black's knight goes to e7 or b8, and Black plays for ...f5 on the kingside while White expands on the queenside with c4.
Plans for White
Fight for d5. Exchange the f6 knight, settle a knight on d5 that cannot be removed, and bring the a3 knight back with c3 and Nc2-e3. The lever a4 against Black's b5 pawn is a common way to open the queenside.
Plans for Black
Play for activity rather than structure. The ...f5 break against e4, the bishop pair and the open g-file in the 9.Bxf6 lines give real counterplay, and the weak d6 pawn and d5 square matter less while Black's pieces are active.
For the wider picture, see the Sicilian Defense guide.