Sicilian Defense: Scheveningen Variation, a6BETA

Often a useful move, since Ndb5 is annoying in case black wants to play Qc7. This takes the position into a hybrid of the Najdorf and Scheveningen.

The Scheveningen is a solid pawn structure, as it sets up a small pawn center that controls the important squares on the 5th rank. However, black has spent a lot of time moving pawns instead of developing pieces, and so white can and should launch a vicious attack in the center and on the kingside before black catches up. The critical tries from white include a fast g4-g5 (possibly with Rg1 and h4 included as well), doing the so-called Keres attack.