Questions about Sicilian Defence

This opening is called the Najdorf variation of the Sicilian Defence. It is one of the most played openings at GM level, ahead of the Dragon or Classical variation.

This is the Kan variation of the Sicilian. I noticed here also the move a6 is played quite early. One can notice this in the Taimonov variation too. But why is it so? Why is a6 such an important often-played move. It does not develop any pieces nor does fight for the center. I understand that it does stop a pin on the knight by the bishop or things like that, and also prepares for maybe a future queen side pawn push, but this pawn is not moved in other openings. I am no expert, but this does really seem a bit silly to me to not develop a piece or push a central pawn. IF you know it, then please explain. :-)

The 5. ... a6 move in the Najdorf serves a number of purposes simultaneously.

1. It stops White from playing either a Bishop or Knight to b5.
2. It makes c7 a safe spot for Black's Queen, allowing it to pressure both the c-file and e5.
3. It supports Black's move b7-b5, which in turn has multiple objectives:
4.  - It guards a Knight outpost on c4. 
5.  - It also threatens to displace White's c3-Knight, creating a threat to the White e-Pawn.
6. - The b7-b5 move also creates a square at b7 for the Black Bishop, again pressuring e4.

Perhaps the best way to see the point of the 5. ... a6 move is to look at a few games.

The reasoning behind a6 is different for the taimanov/kan than it is for the Najdorf.

In the Taimanov (1.e4 c5 2.Nf3 e6 3.d4 cxd4 4.Nxd4 Nc6 5.Nc3 Qc7 6.Be2 a6 7.Be3 Nf6 8.O-O Bb4 9.Na4 and then Black here has a few options), with e6 and c5 played, the d6-square can be a soft spot. It is not Bb5 you are preventing, it is Nb5.

Now you might be saying "But White could play Nb5 on move 5 or 6. Yes, but they are not as good as they would be a little later with pieces developed.

5.Nb5 is to get Black to play 5...d6 (to prevent 6.Nd6+) so that he can play a Maroczy Bind with 6.c4. Note that 5.c4? Is really really bad. In the Accelerated Dragon, Black has played g6 and Bg7. Here, Black has played ...e6. If the Bishop can pin the knight, the Maroczy fails. 5.c4?? Nf6 6.Nc3 Bb4! And it is borderline between White being significantly worse and White being lost. Hence 5.Nb5 d6 first. This version is not nearly as good as the one against the accelerated Dragon.

If 5.Nc3 Qc7 (5...a6 6.Nxc6 bxc6, the dark squares are weak), yes, White can play 6.Ndb5, but there are tactical reasons why it is not an issue for Black, and in some lines, he gives up the Queen for 3 minor pieces. Here, he plays 6...Qb8, keeping an eye on d6 without having to play ...d6 (ideally, Black is trying to get in ...d7-d5 in one go). Black's next move will be ...a6, kicking the knight away.

But in the Taimanov, Black wants to get in ...d7-d5 in 1 shot, but since e6 is played, Black cannot allow White to dominate and occupy d6, blocking the pawn push.

I had played the Taimanov off and on from 2010 to 2015. I cannot say the same for the Najdorf, and while I know a very slight amount of Najdorf theory at the 10,000 foot level, I shall leave the Najdorf part of it for someone else to answer.

But as far as the Taimanov is concerned, it is the Knight, not the Bishop, that needs to kept off of b5 and it is the d6-square that Black cannot allow White to dominate in his mission to get in ...d7-d5.

Hope this at least partially helps. Maybe someone has an explanation for the Najdorf, which is vastly different with ...d6 being played on move 2, and so ...d7-d5 is not a thing in the Najdorf.

Historically, the Najdorf started because after 5... e6 6. Bg5, 6... a6 is stronger than say 6... Nc6 because of 7. Qd2 h6 8. Bxf6 (Bh4? Nxe4) Qxf6 and here 9. Nbd5 hitting d6 would be good without the pawn at a6. Because of other problems, a6 started to be played a move earlier, at move 5. The reason is simple : Black wants more information to better react to what White does. On the queenside, that keeps the option to play Nbd7 or Nc6, or b5 straight away without any of the two, and on the kingside, you keep the three choices : e6, e5, or g6.

If you play 5... g6 straight away, White knows already what the best setup is : Be3 f3 Qd2 0-0-0. If you play 5... e6 then 6. g4 and other things like 6. f4 7. Qf3 are annoying (engine even wants to play e5 losing a full tempo). If you play 5... e5 then 6. Bb5+ (using that b5 square) Nbd7 7. Nf5 a6 8. Ba4 b5 9. Bb3 Nc5 10. Bg5 Bxf5 11. exf5 Be7 12. Bxf6 Bxf6 is a bit better for White.

Now after 5... a6, if 6. Bg5 or 6. Bc4 you know that e6 (covering d5) is correct (or even 6. Bg5 Nbd7). If 6. Be3, 6. Be2 or 6. f4 then 6... e5 is correct. If 6. Bd3 or 6. a4 then 6... g6 makes sense, limiting the potential of the Bd3 or using the fact that 0-0-0 with a4 already played is less attractive for White.

To expand a bit, in the classical Sicilian a6 is necessary and sometimes the queen knight is better at d7 than c6. (So much better that in some lines you end up playing Nc6-b8-d7 then often to c5). So a6 is necessary and gives greater flexibility.

It's 'price' is that Nc6 instead puts immediate pressure on white's center. There are some less common lines that are no problem for the classical but have more venom for Najdorf.

I play both sides of Rauzer vs Classical and Bg5lines vs Najdorf. I dont have a conclusion as to which is more dangerous for black. In the latter, stuff does seem to happen faster though.

- Bill

In the box where you write the text to post, there is a small strip above, the first icon on it (resembling a chessboard) can be used to post diagrams. Hope this helps. Thanks :-)

That's quite a nice line there.

As someone learning the Taimonov, this is massively helpful. Thanks a lot!

Thanks a lot!

This is very helpful. Thank you!

Besides the reasons above, an early...a6 is a waiting move. Both sides are trying to avoid over-committing their pieces. Black in the main line Kan Sicilian after 5. Bd3 Bc5 6. Nb3 can choose to retreat the dark to either e7 or a7. These days I'm playing 6...Ba7 more in the main line Sicilian Kan.

Oh, that's a new perspective too. Thanks for the help!