The position after 1 Nf3 Nf6 2 c4 c5 3 Nc3 Nc6 4 g3 e6 5 Bg2 d5 6 cxd5 Nxd5 can arise from a number of move orders after 1 Nf3. For instance, Black’s first and second moves can be reversed. By playing …Nxd5 instead of …exd5, Black is angling for the Semi-Tarrasch rather than the Tarrasch Defence proper. In the Semi-Tarrasch where White fianchettos his king’s bishop – as he is committed to doing here – Black’s idea is not to avoid an isolated queen’s pawn so much as to make it less easy for White to put pressure on it. The point is that in the Tarrasch, Black has a knight on f6 which protects d5, but White will have a knight on c3 and will usually play Bg5, threatening to win the pawn. In the Semi-Tarrasch, that possibility is removed. On the other hand, exchanges tend to reduce the attacking possibilities of the player with the isolated queen’s pawn. We shall see how these differences play out below.
White starts with 7 0-0 and Black usually replies 7…Be7, as the various retreats of the knight (7…Nc7?!, 7…Nf6?!, 7…Nb6) don’t seem effective. White then takes the opportunity to play 8 d4.
Black usually replies 8…0-0. The alternative is 8…cxd4 9 Nxd5 exd5 (9…Qxd5 is met by 10 Nxd4! when 10…Qxd4?? 11 Bxc6+ is not recommended, so Black ends up with a weak pawn on c6 after Nxc6) 10 Nxd4 0-0 11 Be3 leads to an isolated queen’s pawn where the exchange of knight has benefitted White, as Black lacks play based on …Ne4 or …Ng4.
After 8…0-0, Khalifman recommends 9 Nxd5!? since he considers that 9 e4 can be met effectively by 9…Ndb4 or 9…Nb6, rather than 9…Nxc3 10 bxc3, when White has a strong pawn centre.
After 9 Nxd5 exd5 (9…Qxd5 is bet met by 10 Be3) 10 dxc5 Bxc5 11 Bg5! we have the basic starting position of this line. The disruptive move of the bishop to g5, equally effective without a knight on f6, seems the most challenging for Black.
- 11…f6 12 Bd2! Bf5 13 Qb3 Bb6 14 Be3! White forces exchanges, aiming to reach a favourable endgame. (See Kramnik – Kengis, Riga 1995)
- 11…Qd7 12 Ne1 (intending to redirect the knight to d3) d4 13 Nd3 Bb6 14 a4. White looks to squeeze Black on the queenside. (See Topalov – Hansen, Istanbul Olympiad 2000)
- 11…Qb6 12 Rc1 d4 13 Qc2 Bd6 14 Nd2 Be6 15 Ne4. White eyes the weak c5 square. Illescas Cordoba – Lautier, Dos Hermanas 1994 went 15…Be7 16 Bxe7 Nxe7 and now Khalifman recommends 17 Qc5!? Nf5 (17…Nc6 18 Nd6) 18 Qxb6 axb6 19 a3 with the better endgame.