Blake, winner of this tournament two years ago, was a 6-2, 6-0 winner over Yen-Hsun Lu. Tursunov, seeded third, had to rally to down Paul Capdeville 3-6, 6-3, 6-1.
Tursunov and Blake will meet in Saturday's semifinals.
In the other quarterfinal matches, No. 2 seed Gilles Simon eliminated Tommy Haas 4-6, 6-4, 6-2 and Sam Querrey fought off Bobby Reynolds 6-1, 3-6, 6-3.
Simon was down a break in the second set before beginning his comeback.