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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 c6
3. Nf3 Nf6
4. Nc3 e6The position may readily be reached by a number of different move orders. Black's supporting pawns resemble a mixture of the Orthodox Queen's Gambit Declined, e6, and the Slav Defense, c6.
Black is threatening to capture the white pawn on c4 and hold it with ...b7–b5. White can avoid this in a number of ways. About 80% of games continue 5.Bg5 or 5.e3: the former constitutes a sharp pawn sacrifice, while the latter restricts the dark-squared bishop from its natural development to g5. Other possible moves are 5.Qb3, 5.g3 and 5.cxd5, the last of which, after 5...exd5, leads to a line of the QGD Exchange Variation where White's early Nf3 enables Black's queen bishop to freely develop, which should give equality (ECO codes D43 and D45). It is worth noting that 5.Bf4 is considered somewhat inaccurate, as 5...dxc4 is favorable for Black.
The Semi-Slav is designated by codes D43 through D49 in Encyclopaedia of Chess Openings.
First moves and possible deviations
It is possible to reach the Semi-Slav through many move orders. White may start the game with either 1.d4, 1.Nf3 or even 1.c4, keeping the possibility of a Semi-Slav open. Black can choose different combinations of ...d5, ...c6, ...e6 and ...Nf6 as well in order to avoid certain variations or to open up some new opportunities of his own. This chapter looks at the first moves of the game from Black's point of view, assuming that he would prefer to play the Semi-Slav.
1.d4 d5 move order
If White opens the game with 1. d4, Black is happy to respond with 1...d5 when aiming for a Semi-Slav. Of course White can continue the game with 2. Bf4 or even 2. Bg5 (as is the case if Black opens 1...Nf6), and the game will take a completely different path. In vast majority of the games, however, White players choose to play either 2. c4 (Queens Gambit) or 2. Nf3. After 2. Nf3, the natural continuation for Black is 2...Nf6. Playing 2...c6 or 2...e6 might be somewhat inaccurate, since White always has the option of avoiding c2-c4, so developing the knight first makes a lot of sense.
If White chooses the most common 2. c4, Black has three practical choices: either protect the pawn on d5 by playing e6 or c6 (keeping the option of a Semi-Slav open), or alternatively capture the white pawn with dxc4 (leading to Queen's Gambit Accepted). The first thing for Black players to consider is, what if White captures on d5 anyhow with cxd5. If Black has played the Slav move order (2...c6), then after the recapture cxd5 ("exchange Slav") the pawn structure is symmetrical. Should Black have played 2...e6 instead, the recapture exd5 leads to an imbalanced pawn structure called the Carlsbad structure, which might offer White some opportunities for a minority attack on the queenside.
Slav move order: 2...c6
Protecting the d5-pawn with the c-pawn has at least three implications for Black. First, it allows Black to keep the option to enter the Slav Defence, i.e., developing his light-squared bishop to f5 at the appropriate moment, before moving his e-pawn. Second, it may discourage White from capturing on d5, given the somewhat drawish reputation of the Exchange Slav. Third, it prevents White from entering the Catalan opening with 3.g3.
One drawback of playing 2... c6 is that White may continue 3. Nf3, and after 3... Nf6 play 4. e3 ("Slow Slav"), and now Black cannot really play the Semi-Slav since 4...e6 is considered to be good for White as he has not committed to Nc3 thus having other options to develop, for example Nbd2 or b3.
Queen's Gambit declined move order: 2...e6
Protecting the d5-pawn with the e-pawn allows Black to develop his kingside more rapidly, but it does block the light-squared bishop for the time being. After 3.Nf3 Nf6 White has the option of entering the Catalan opening with 4.g3.
If White continues 3. Nc3, Black has two options to proceed with a Semi-Slav in mind. First, Black can play 3... c6 (the "triangle setup", see below). Second, Black can play 3... Nf6, which gives White the opportunity to continue 4. cxd5 exd5 followed by 5. Bg5.
The triangle setup
After the move order 1. d4 d5 2. c4 c6 3. Nc3 Black has the opportunity to respond with 3... e6 instead of 3...Nf6. This "triangle setup" opens up some new alternatives for both players on the fourth move.
First, White has the opportunity to enter the Marshall Gambit by playing 4. e4. Play continues 4... dxe4 (4...Bb4 is sometimes played, but should favor White) 5. Nxe4 Bb4+. Now White has two alternative paths to continue. The main line is considered to be 6. Bd2 Qxd4 7. Bxb4 Qxe4+ and then White blocks the check with either his knight or bishop. Alternatively White can continue with 6. Nc3 (as in World Championship match Carlsen–Anand, 2013), and play continues 6... c5 7. a3 Ba5.
Second, if White continues 4. Nf3, Black has the extra option of playing 4...dxc4 entering the Noteboom variation. If White wants to avoid this variation, he must play either 4. e4 (Marshall Gambit) or 4.e3 (which usually transposes to the Meran, but deprives White of the Bg5 variations). White now has a number of possible continuations, including 5. a4 (see below), 5. e3 (often transposing to the line given below), 5. e4 (with similarities to the line given below), or even 5. Bg5. A typical line in the Noteboom variation continues: 5. a4 Bb4 6. e3 b5 7. Bd2 a5 8. axb5 Bxc3 9. Bxc3 cxb5 10. b3 Bb7 11. bxc4 b4 12. Bb2 Nf6 13. Bd3 Nbd7 14. 0-0 0-0 with an interesting position where Black has two connected passed pawns on the queenside, while White has the bishop pair and dominates the center of the board.
It is worth noting that the "triangle setup" is not ideal for Black if White plays 3. Nf3 instead of 3.Nc3. Should Black play 3... e6 nevertheless, White has the option of continuing with 4. e3 or 4. Qc2, for example, thus avoiding the Noteboom variation.
1.d4 Nf6 2.c4 e6 move order
Black has the option of delaying the move ...d7–d5, for instance to avoid the exchange cxd5. If White continues 3. Nc3, Black has the option of transposing to a Nimzo-Indian with 3... Bb4. Should White choose to play 3. Nf3 instead, Black can simply play 3... d5, and then after 4. Nc3 c6 we are back at the start of the Semi-Slav. This move order, however, allows White to play the Catalan Opening with either 3. g3, or alternatively 3. Nf3 d5 4. g3.
Semi-Slav: 5.e3 variations
Roughly 50% of the games continue with 5. e3. White gives priority to developing his light-squared bishop, and accepts that for the time being the dark-squared bishop will remain somewhat out of play. The main line continues with 5... Nbd7. The bishop moves 5...Bd6 and 5...Be7 are 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. Th.... Discover the Noteboom Tutorials popular books. Find the top 100 most popular Noteboom Tutorials books.