The Slav Defense is a chess opening that begins with the moves:
- 1. d4 d5
- 2. c4 c6
The Slav is one of the primary defenses to the Queen's Gambit. Although it was analyzed as early as 1590, it was not until the 1920s that it started to be explored extensively. Many masters of Slavic descent helped develop the theory of this opening, including Alapin, Alekhine, Bogoljubov, and Vidmar.
The Slav received an exhaustive test during the two Alekhine Euwe World Championship matches in 1935 and 1937. Played by 11 of the first 13 world champions, this defense was particularly favored by Euwe, Botvinnik, and Smyslov. More recently the Slav has been adopted by Anand, Ivanchuk, Lautier, Short, and other top grandmasters, including use in six of the eight games that Vladimir Kramnik played as Black in the 2006 World Championship (in the other two, he played the related Semi-Slav Defense).
Today the theory of the Slav is very extensive and well developed.
Black faces three major problems in many variations of the Queen's Gambit Declined (QGD):
- Development of the black queen bishop is difficult, as it is often blocked by ...e6.
- The pawn structure offers White targets, especially the possibility of a minority attack on the queenside in the Exchange variation of the QGD.
- White often plays Bg5 to pin the black knight on f6 against the black queen, and unpinning it is awkward for Black.
The Slav addresses all of these problems. Black's queen bishop is unblocked; the pawn structure remains balanced; and the move Bg5 is not yet a threat as the unmoved black pawn on e7 prevents the pin. Also, if Black later takes the gambit pawn with ...dxc4, the support provided by the pawn on c6 allows ...b5 which may threaten to keep the pawn, or drive away a white piece that has captured it, gaining Black a tempo for queenside expansion.
On the other hand, Black usually will not be able to develop the queen bishop without first giving up the center with ...dxc4, and developing this bishop may leave the black queenside weak. Additionally, the thematic break ...c5 incurs the loss of a tempo.
The Slav can be entered by many move orders. The possibilities include 1.d4 d5 2.Nf3 Nf6 3.c4 c6, 1.Nf3 d5 2.c4 c6 3.d4 Nf6, and so on. From the standard Slav position (1.d4 d5 2.c4 c6), the most important continuations are
- 3.Nc3 e5 (Winawer Countergambit)
- 3.Nc3 e6 (Semi-Slav Defense)
- 3.cxd5 cxd5 (Slav Exchange Variation)
- 3.Nf3 e6 (Semi-Slav Defense)
- 3.Nf3 Nf6 4.Nc3 (main line)
- 4...dxc4 (Slav Accepted)
- 5.a4 (Alapin Variation)
- 5...Na6 (Smyslov Variation)
- 5...e6 (Soultanb ieff Variation)
- 5...Bf5 (Czech Variation)
- 6.e3 (Dutch Variation)
- 6.Ne5 (Krause Attack)
- 5...Bg4 (Steiner Variation)
- 5.e3 (Alekhine Variation)
- 5.e4 (Slav Gambit)
- 4...e6 (Semi-Slav Defense)
- 4...g6 (Schlechter Variation)
- 3.Nf3 Nf6 4.e3 (Slav Declined)
Black can also transpose into the Semi-Slav Defense by playing ...e6 on either the third or fourth move. The Semi-Slav Defense, a kind of a combination Queen's Gambit Declined and Slav Defense, is a very complex opening in its own right. See Semi-Slav Defense for details.
After 3.Nc3, the pressure on Black's center prevents 3...Bf5?, since after 4.cxd5 cxd5 5.Qb3 White wins a pawn. Another Black try that doesn't work is 3...Nf6 4.e3 Bf5 5.cxd5 cxd5 6.Qb3 Bc8 and now f4 and Nf3 followed by Ne5 gives White a big advantage. Black can try the Winawer Countergambit, 3.Nc3 e5, which was introduced in Marshall Winawer, Monte Carlo 1901, but usually Black transposes into the Semi-Slav with either 3...e6 or 3...Nf6 4.Nf3 e6.
The Slav Exchange Variation "is the system that takes the fun out of playing the Slav" for Black. After 3.cxd5 cxd5, the symmetrical position offers White only the advantage of the extra move, but the drawish position offers Black little chance to win unless White is overly ambitious. The rooks will often be exchanged down the now open C-file. To avoid this possibility Black often chooses the move order 2...e6 followed by 3...c6 to enter the Semi-Slav.
White's other knight move is more popular than Nc3. White can avoid the complexities of the Slav Accepted by entering the Slav Declined with 3.Nf3 Nf6 4.e3. A common continuation is 4...Bf5 5.cxd5 cxd5. White will try to take advantage of the absence of Black's queen bishop on the queenside, but this isn't enough to gain an advantage if Black plays accurately. Another way to play is 4...Bg4. This also equalizes easily.
The a6 Slav occurs after 4...a6. Black seeks an early b5, either before or after capturing at c4.
- This try sees an important space advantage for white. Both e5 and b6 become important pawn breaks for black. White will often play his bishop to f4, controlling the important dark squares e5, d6, c7, and b8 (this last square reduces black's control over the b-file should it open)
- Bf5 6.Bf4 Nbd7 7. h3 e6 8.e3
Main Line, Slav Accepted
The main line continues 3.Nf3 Nf6.
A line that is similar to the Catalan Opening is 4. Qc2. Often, White will fianchetto his Light Square Bishop. This has the disadvantage of White's Queen being somewhat exposed on c2. Black can continue 4...g6, intending 5...Bf5. White usually plays 5.Bf4 so that after 5...Bf5 6. Qb3 Qb6 White can play 7. c5! Black has to play 7...Qxb3, which will be met by 8.axb3. White has a moderate advantage in this Queenless middlegame, as white can expand on the queenside and try to create on the queenside.
The main line continues 4. Nc3.
Black shouldn't play 4...Bf5 because White will gain the advantage with either 5.Qb3 or 5.cxd5 followed by 6.Qb3. Traditionally Black had a choice between 4...e6 and 4...dxc4 before developing the queen bishop, but in the 1990s 4...a6 was introduced, with the idea of developing the queenside without locking in the queen bishop or conceding the center. As before, 4...e6 transposes into the Semi-Slav.
The Slav Accepted continues with 4...dxc4.
5.e4 b5, Slav Gambit
White's sharpest try is the Slav Gambit, 5.e4 b5. White will then usually continue with the Geller Tolush Gambit, 6.e5 Nd5 7.a4 e6, but it is unclear whether the attack is strong enough for the sacrificed pawn. Evaluation of this line changes as improvements are found, but as of 2005 it is generally thought to favor Black.
White maintains the pawn
White's other choices in the Slav Accepted are 5.e3 (Alekhine Variation) and 5.a4 (Alapin Variation). Both moves are popular, with 5.e3 being more solid and 5.a4 being more aggressive.
5.e3, Alekhine Variation
5...b5 6.a4 b4 7.Na2
- 7...e6 8.Bxc4 a5
- 7...Ba6 8.Nbd2 c3 9.bxc3 Bxf1 10.Nxf1 bxc3
5.a4, Mainline, Alapin Variation
With 5.a4 White acts against ...b5 and prepares 6.e4 and 7.Bxc4.
Black has several viable responses to White's pawn advance 5.a4:
The 5...a6 lines can be tricky. Black prepares to hold on to the gambit pawn with ...b5, and the game may transpose into the complex Meran Variation of the Semi-Slav.
5...Na6, Smyslov Variation
With the Smyslov Variation, 5...Na6, Black allows the e-pawn to come to e4 but can gain counterplay by ...Bg4 and perhaps bringing the knight to b4 e.g. 6.e4 Bg4 7.Bxc4 e6 8.0-0 Nb4.
5...Bf5, Mainline, Czech Variation
The Czech Variation can be considered the main line. With 5...Bf5, Black prevents 6.e4.
6.e3, Dutch Variation
- If White plays 6.e3 (Dutch Variation), play can continue 6...e6 7.Bxc4 Bb4 8.0-0 0-0 with a fairly quiet game. Black can also play 6...Na6 with the idea of 7...Nb4, known as the Dutch, Lasker Variation.
6.Ne5, Krause Attack
- A more energetic line begins 6.Ne5 (Krause Attack) where White intends f2 f3 and e2 e4 or Nxc4, perhaps followed by a fianchetto of the king bishop with g2 g3 and Bg2.
Black can try either 6...Nbd7 7.Nxc4 Qc7, which may leave White a bit better, or 6...e6 7.f3 Bb4, when 8.e4 Bxe4 9.fxe4 Nxe4 is a complex piece sacrifice with the possible continuation 10.Bd2 Qxd4 11.Nxe4 Qxe4+ 12.Qe2 Bxd2+ 13.Kxd2 Qd5+ 14.Kc2 Na6.
5...Bg4, Steiner Variation
In the Steiner Variation (also called the Bronstein Variation), 5...Bg4, White may be discouraged from e4 by the possibility 6.e4 e5. More often the game continues 6.Ne5 Bh5.
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