My critical opening position in the Sicilian
My favourite plan against the Sicilian is 3. Bf1-b5, pinning a Nc6 or giving check. I stick to this plan since a strong (2200) player has admitted after the game (equal until I blundered in the endgame) that he hates Bb5 in the Sicilian. Another reason is Deep Shredder, considering it the best move against 2.-Nc6.
The critical line for my plan is thus 1. e4 c5 2. Nf3 e6 where I can neither pin a knight nor give a check.
The main purpose of e6 is a fast counterstrike d5 against White's center pawn, and if Black manages to reach this goal, he has an easy and equal game. White therefore has no time for slow moves such as c3, preparing d4 with equal pawn force in the center. If he wants to keep an advantage, he must prevent d5. The best move is 3.Nc3, keeping control over d5 and developing a second piece against none of Black.
Black now can prevent 4. Bb5 by 3.- a6, but the most played move is 3. - Nc6, allowing my thematic 4. Bb5. If Black attacks it by a6, I trade bishop against knight, and Black's double pawn and his lag in development give me a good compensation for the bishop pair.
White to move.
But Black can double his knights, playing 4. - Nge7. This is a critical position because after BxN NxB, Black has no double pawn and replaced his strong Nc6, and I have no sufficient compensation for the bishop pair. White therefore is forced to take action, and the best choice is 5. d4, of course.
That is, in this position I have to change my general plan, opening the position because keeping it closed will lose my advantage, allowing Black to equalize easily.