I had thought of that, but it still seems like a waste of a move because couldn't you just play e5 then Bd7 when in check? Or does that lead to an inferior variation?
Sicilian Najdorf
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To take away the annoying square b5 from the knight
5. ...a6 is an important move. It prepares ...b5, gaining Queenside space and bringing the Light square bishop to a strong post on b7 where it eyes the all important d5 square and e4 pawn, takes away the b5 square from White's knights and bishop, and prepares ...e5 without the threat of Bb5+.
What's the point of a6? http://www.chess.com/opening/eco/B90_Sicilian_Defense_Najdorf_Variation