Chess Opening Theory/1. d4/1...Nf6/2. c4/2...e5/3. dxe5/3...Ng4/4. Bf4/4...Nc6/5. Nf3/5...Bb4/6. Nbd2/6...Qe7/7. e3/7...Ngxe5/8. Nxe5/8...Nxe5/9. Be2

1.d4 Nf6 2.c4 e5 3.dxe5 Ng4 4.Bf4 Nc6 5.Nf3 Bb4+ 6.Nbd2 Qe7 7.e3 Ngxe5 8.Nxe5 Nxe5 9.Be2

In this variation White tries to avoid the move a2–a3 in order to gain a tempo over the 7.a3 variation. After the standard moves 7...Ngxe5 8.Nxe5 Nxe5 9.Be2 Black has the main line 9...0-0 or the less-explored 9...b6. While 9...0-0 will give him the option on the tenth move to keep his Bb4 bishop or part with it, 9...b6 is more forcing as Black will be more or less compelled to exchange his bishop for the Nd2.

Lalic thinks the strategies in which Black gives up the bishop pair (by exchanging its Bb4 for the Nd2) for nothing are a mistake. He does not like the strategy to retreat the Bb4 in d6 either, because they are too drawish. He recommends the strategy to retreat the bishop in c5, and keep it there thanks to the push a7–a5.

Black gives up the bishop pair with 9...b6
1.d4 Nf6 2.c4 e5 3.dxe5 Ng4 4.Bf4 Nc6 5.Nf3 Bb4+ 6.Nbd2 Qe7 7.e3 Ngxe5 8.Nxe5 Nxe5 9.Be2 b6

With 9...b6 Black intends to compensate the loss of the bishop pair (once he has exchanged his Bb4 for the Nd2) by the activity of his other bishop on the long diagonal, reasoning that White will have difficulties to do the same as his Be2 cannot go on the f3-square without being exchanged against the Ne5. The drawback of 9...b6, however, is that the b6-square is not available for the Bb4 anymore, so that this bishop will soon lack retreat squares.

Indeed, after 10.0-0 it would be dangerous to keep his Bb4 because White could start an attack aiming at harassing the black bishop. For instance in the game Etchegaray - Sebban after 10...Bb7?! 11.Nb1 a5 12.a3 Bc5 13.Nc3 Black committed suicide with the natural 13...d6??, and after the tactical sequence 14.b4! axb4 15.axb4 Rxa1 16.Qxa1 Bxb4 17.Qa4+ Nc6 18.Nd5 White wins a piece. Another example is the direct 10...Bb7?! 11.Nf3!? and unfortunately Black cannot take with his knight as after 12...Nxf3 13.Bxf3 Bxf3 14.Qxf3 both his Ra8 and his c7-pawn would be attacked.

Therefore, Black has to exchange his Bb4 for the Nd2. After 10...Bxd2 11.Qxd2 Bb7 White has indeed gained a tempo as he provoked the exchange of the Bb4 against the Nd2 without having to play a2-a3. This tempo gained will allow him to realize the push c4-c5 before Black has setup his defenses to avoid it. White can prepare the push c4–c5 with the b2–b4, with Qc3 and/or with Rac1, for instance:
 * In the game Solozhenkin – Stiazhkin (Leningrad 1990), White tried the immediate sacrifice 12.c5!? bxc5 13.Qa5 and after 13...d6 14.Bxe5! dxe5 15.Rfc1 White stands much better. However Black improved on these moves in the game Flear – Blatny (Andorra 1993) by giving immediately the pawn back with 13...Ng6! 14.Qxc7 Nxf4 15.Qxf4 0-0 and Lalic thinks the situation is balanced.
 * After 12.Qc3 the natural 12...d6!? leads after 13.c5 bxc5 14.Bxe5 Qxe5 15.Qxe5+ dxe5 16.Rac1 0-0-0 17.Rxc5 to a superior ending for White, although Lalic thinks Black should hold. Therefore another possibility for Black is trying to do without the move d7-d6, as in the game Gausel – Reite (Norwegian Team Championship, 1991) with 12.Qc3 f6 13.b4 c5!? which is a radical way to remove the c4-c5 threat.
 * In the game Alterman – Blatny (Pardubice 1993), White took his time to prepare the c4–c5 push, with 12.Rac1 d6 13.b4 0-0 14.c5 dxc5 15.bxc5 Rad8 16.Qc3 Ng6 17.Bg3 Rd5 18.cxb6 cxb6 19.Rfd1 Rfd8 20.Rxd5 Rxd5 21.a3 and White has succeeded in freeing his bishop pair, so he has an edge. Therefore the same Black player tried to improve his play in the game Chernin – Blatny (Brno 1993) with the immediate retreat 13...Ng6 but after 14.Bg3 0-0?! 15.c5 dxc5 16.bxc5 Rfd8 17.Qb4 White also had the initiative. Instead, Chernin suggests a wholly different plan with 14...h5!?, intending to force the exchange of the Bg3 against the Ng6, develop the Rh8 through the h6-square and put the King on f8 instead of castling.

Black gives up the bishop pair with 9...0-0
1.d4 Nf6 2.c4 e5 3.dxe5 Ng4 4.Bf4 Nc6 5.Nf3 Bb4+ 6.Nbd2 Qe7 7.e3 Ngxe5 8.Nxe5 Nxe5 9.Be2 0-0

When Black goes for it with 10...Bxd2, he runs the risk to end up a tempo down over the 7.a3 variation and to be soon unable to meet White's positional threats on the queenside. White can avoid the push a2–a3 and continue with the standard plans of the 7.a3 variation. Tseitlin considers the main variation is 9.Be2 d6 10.0-0 Bxd2 11.Qxd2 0-0 12.Rfd1 b6 13.b4 Bb7 14.c5 dxc5 15.bxc5 and then gives a line he analysed in which Black ends a pawn down but in a drawish position. Similarly, after the moves 9.Be2 Bxd2+ 10.Qxd2 d6 11.0-0 0-0 Lalic notices: "by exchanging so early on d2 and castling quickly Black has saved himself the worry of how to meet Nb3 and what to do with his king, but such simplistic logic is in no way going to guarantee him a comfortable game."

However, everything is not that bad for Black. First, to implement his plan White has to concentrate on development (9.Be2, 10.0-0) before he turns his attention to the queenside. That means Black has more time to organise his play than in the 7.a3 variation, notably to organise a blockade of the c5-square. Moreover, as White does not put immediate pressure, Black is not compelled to castle rapidly and he can keep his king in the centre for a longer time, or even castle queenside. Hence Lalic note that "White has not wasted time with a2–a3, but in fact it is not so easy to capitalise on this extra tempo."

Black does not exchange its Bb4 for the Nd2
''1.d4 Nf6 2.c4 e5 3.dxe5 Ng4 4.Bf4 Nc6 5.Nf3 Bb4+ 6.Nbd2 Qe7 7.e3 Ngxe5 8.Nxe5 Nxe5 9.Be2 0-0 10.0-0

After 10.0-0 the Nd2 is not pinned anymore, so this is the last moment when Black can be certain to have the possibility to exchange it for its Bb4.

Apart from the exchange of the Bb4 for the Nd2, another option, resurrected and enriched by the grandmaster Pavel Blatny, is to exchange the Bb4 against the Bf4. This can be achieved via 10...Ng6 11.Bg3 (11.Bxc7?? d6 loses a piece) 11...Bd6 12.Bxd6 Qxd6. White still has possibilities to play for an advantage due to his advance of development, his space advantage on the queenside and the remote possibility to install his knight on the good square d5. For example the possible 13.Ne4 Qxd1? 14.Rfxd1 d6 15.c5! dxc5 16.Nxc5 c6 17.Rac1 is uncomfortable for Black who is still underdevelopped. The game Stohl – Blatny (Prague 1996) shows the proper way for Black with 13.Ne4 Qe5 14.Nc3 b6 15.Qd5 and here Blatny introduced the novelty 15...Ba6! that breathed new life to this variation as Black has succeeded in equalising. After the tactical sequence 16.Qxe5 Nxe5 17.Nd5 c6 18.Nc7 Bxc4 19.Bxc4 Rac8! Black regains the sacrificed piece and the endgame is equal.

The other possibility for Black is to keep his Bb4 as long as possible, exchanging it against the white knight only in favourable circumstances. A couple of attempts have been done with this in mind, with subtle variations along the moves a7–a5 and b7–b6:
 * Against the mundane 10...d6 White can continue with 11.Nb3 (see diagram at right), intending a2-a3, to play on the queenside against the exposed Bb4. Black needs to fight for the dark squares b4 and c5, in order to avoid problems for its dark-squared bishop. After 11.Nb3 b6 12.a3 Bc5 13.Nxc5 bxc5 authors thought Black had an equal game with good play on the B-file, until the game Karpov – Short (first game in their 1992 candidate match at Linares) where White continued with the immediate 14.b4! and Black cannot really take in b4 because the a7-pawn would remain weak. Hence the game continued with 14...Nd7 15.Bg4 and White is calling the shots. Another path for White is 11.Nb1 to recycle the knight on his ideal square d5. Lalic does not consider this as dangerous for Black, on the account of 11...a5 12.a3 Bc5 13.Nc3 Be6 14.b3 f5! with a strong control of the centre.
 * The same move 10...d6 can be played with the different idea 11.Nb3 a5. After the logical 12.a3 Bc5 13.Nxc5 dxc5 White has a pawn majority on the kingside that Black hopes to immobilise, and counterattack on the c4-pawn. The Ra8 can be quickly developed along the sixth rank.
 * A third idea is the immediate 10...a5, to have the d6-square for the bishop, impeach the b2–b4 push and having the possibility a5–a4 if the white knight comes on b3. In the game Mikhalevski – Chabanon (Bad Endbach 1995), Black succeeded in keeping the bishop with 11.Nb3 a4 12.a3 Bd6 13.Nd4 Bc5 14.Nb5 d6 15.Nc3 Ng6 16.Bg3 f5 with dynamic play.

Theory table
1.d4 Nf6 2.c4 e5 3.dxe5 Ng4 4.Bf4 Nc6 5.Nf3 Bb4+ 6.Nbd2 Qe7 7.e3 Ngxe5 8.Nxe5 Nxe5 9.Be2