Semi-Slav Defense

Semi-Slav Defense
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Moves 1.d4 d5 2.c4 e6 3.Nc3 Nf6 4.Nf3 c6
ECO D43–D49
Parent Queen's Gambit
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The Semi-Slav Defense is a variation of the Queen's Gambit chess opening, defined by the position reached after the moves:

1. d4 d5
2. c4 e6
3. Nc3 Nf6
4. Nf3 c6

The position may readily be reached by a number of different move orders. With Black advancing pawns to both e6 and c6, the opening resembles a mixture of the Orthodox Queen's Gambit Declined and the Slav Defense.

With 4...c6, Black threatens to capture the white pawn on c4, and hold it with ...b7–b5. White can avoid this with 5.e3, though at the cost of restricting the dark-squared bishop from its natural development to g5. Alternatively, White often gambits a pawn with 5.Bg5, the Anti-Meran Gambit, which Black may accept with 5...dxc4 6.e4 b5, leading to sharp play, or decline with 5...h6, the Moscow Variation. If Black plays the latter variation, White can play 6.Bxf6 Qxf6, ceding the bishop pair in exchange for a lead in development and a freer game, or again offer a gambit with 6.Bh4!?

For the Semi-Slav the Encyclopaedia of Chess Openings designates codes D43 through D49.

Contents
This article uses algebraic notation to describe chess moves.

Main variations

About 80% of games continue 5.Bg5 or 5.e3. Other possible moves are 5.cxd5 and 5.g3.

5.e3

The main line continues with 5.e3, when Black usually develops with 5... Nbd7; though a bishop move 5...Bd6 or 5...Be7 is seldom seen, as masters realized early on that at e7, the bishop was passively placed and does nothing to further one of Black's aims, the freeing move ...e5. The unusual move 5...a6 appears solid for Black.

Meran Variation

The main variation of the Semi-Slav is the Meran Variation, 5.e3 Nbd7 6.Bd3 dxc4 7.Bxc4 b5, (ECO codes D46 to D49), when play usually continues with 8.Bd3, with 8.Be2 and 8.Bb3 less common alternatives. The line was first played in 1906 in the game Schlechter–Perlis.[1] The variation takes its name from the town of Meran (Merano) in northern Italy. During a 1924 tournament in Meran, it was used successfully in the game Gruenfeld–Rubinstein. Gruenfeld adopted the same variation two rounds later against Spielmann, winning as well.[2] Viswanathan Anand won two games with Black in his World Chess Championship 2008 match with Vladimir Kramnik. Black surrenders his outpost on d5, gaining a tempo for queenside space expansion by ...b7–b5. White will play in the center, leading to a rich, complicated game. These opposing strategies, with the ensuing keen play, have long made the Meran a favorite for enterprising players of either color. An example is Gligoric v Ljubojevic, Belgrade, 1979.

Anti-Meran Variation

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Position after 7.g4

If White wants to avoid the Meran Variation without entering the complexities of the Anti-Meran, 5.cxd5 or 5.Qb3 are possibilities, though after 5...exd5, the former leads to a line of the QGD Exchange where White's Nf3 enables the Black QB to freely develop, which should give equality (ECO code D43 and D45). After 5.e3 Nbd7, the main alternative to 6.Bd3 has become 6.Qc2, waiting for Black to commit to ...dxc4 before playing Bd3. Once a sideline, this move exploded in popularity in the 1990s, in large part due to Anatoly Karpov's advocacy.

Shirov–Shabalov Gambit in Anti-Meran

Another increasingly common gambit line used in the Anti-Meran system variation is the sharp 5.e3 Nbd7 6.Qc2 Bd6 7.g4. Popularized by Alexander Shabalov and Alexey Shirov, the gambit destabilizes the center for Black and has been successful for several grandmasters, including Kasparov. It has also been successful against computers, in games such as Kasparov vs. Deep Junior, Game 1.

5.Bg5

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Position after 5.Bg5 dxc4

The Anti-Meran Gambit (ECO code D44) arises after 5.Bg5. Possible replies include ...h6, ...Nbd7, ...dxc4, and ...Be7. White refuses to shut in the dark-squared bishop, instead developing it to an active square where it pins the black knight. It is now possible for Black to transpose to either the Cambridge Springs Defense with 5...Nbd7 6.e3 Qa5, or enter the Orthodox Defense with 6...Be7.

Botvinnik Variation

This line is extremely complicated, with theory stretching past move thirty in some variations. Black captures a pawn by 5...dxc4. White takes control of the center with 6.e4 as Black defends with 6...b5. The main line of the Botvinnik now continues 7.e5 h6 8.Bh4 g5 9.Nxg5 hxg5 10.Bxg5 Nbd7. White will regain his piece with interest, emerging with an extra pawn, but Black will soon complete his development, gaining great dynamic compensation, whereas White's task is rather more difficult. White will fianchetto his king's bishop and castle kingside, while Black will play ...c5, ...Qb6, castle queenside, and can carry out an attack in the center or on either flank, leading to complex play. The opening was introduced by Mikhail Botvinnik in the 1945 USSR vs USA radio match vs Arnold Denker. Today, Alex Yermolinsky has an excellent record with the White pieces and Alexei Shirov has been Black's chief proponent in this variation.

Moscow Variation

The Moscow Variation 5.Bg5 h6 6.Bxf6 Qxf6 gives rise to play of a different character from the lines after 5...dxc4. Black has the bishop pair, which gives him good long-term chances, but must avoid prematurely opening the position in the face of White's superior development and central control, as his position is initially solid but passive. Alexei Dreev has played this line successfully as Black. The gambit line 6.Bh4 (the Anti-Moscow Variation) was once considered dubious, but has seen a recent resurgence. In return for the pawn, White receives a lead in development and a strong initiative. This dynamic mode of play, which is characteristic of the modern game, has seen this line being played by many strong grandmasters, though the theoretical verdict is unclear.

Alternatives after 5.e3 Nbd7 6.Bd3

Though appearing in contemporary master play with less frequency than the Meran, there are other possibilities: 6...Be7, 6...Bb4, introduced by the Italian master Max Romih, and 6...Bd6, which was much the most popular line before the debut of the Meran, and espoused by the American grandmaster Arthur Bisguier throughout his career.

After 6...Bd6, 7.0-0 0-0 8.e4 dxe4 9.Nxe4 Nxe4 10.Bxe4 is the most common line. There are now several alternatives for Black, with one a clear error, as it loses a pawn: 10...e5 11.dxe5 Nxe5 12.Nxe5 Bxe5 13.Bxh7+ Kxh7 14.Qh5+ Kg8 15.Qxe5. This line, however, has a strong drawish tendency in practice, due to the opposite-colored bishops, though all the heavy pieces remain on the board.

Black's other choices include 10...c5, though theory regards this as premature as it enables White to play for a kingside attack with 11.Bc2, followed by Qd3 and Bg5. 10...Nf6 has also been played, but this misplaces the knight and does nothing to further Black's play against the centre by means of the pawn breaks ...c5 or ...e5. Bisguier preferred 10...h6 and it has come to be considered the strongest plan.

The other ideas, 6...Be7, which has the same drawback as after 5.e3 Be7, and 6...Bb4, have become sidelines in modern play.

Notes

  1. ^ http://www.chessgames.com/perl/chessopening?eco=D48
  2. ^ "An Opening Created in 1924 Still Leads to Complex Battles", New York Times , 29 January 2006

References and further reading