Klay Thompson wouldn't let surprising Washington State go down.

Thompson forced overtime with a tying 3-pointer with 15 seconds left and hit some clutch shots down the stretch to help the Cougars top host Santa Clara 85-79,Sunday night.

Santa Clara (5-6) led by six at half and extended its lead to nine with 8:16 to play. But the Cougars (8-1) refused to go away and kept within striking distance, setting up Thompson's big shot at the end of regulation. The junior guard put Washington State up five with 1:19 to go in overtime with his third 3-pointer of the game and then sealed the comeback victory with four free throws in the final minute.

Thompson finished with a team-high 21, and DeAngelo Casto and Reggie Moore each added 15 for the Cougars, who have now won three straight since suffering their only of the season to No. 5 Kansas State.

Santa Clara's Kevin Foster led all scorers with 29 points, but missed a potential game-winning 3-pointer at the end of regulation.

Washington State heads to Honolulu for the Hawaiian Airlines Diamond Head Classic. They'll open play against Mississippi State Wednesday and battle a field that includes No. 9 Baylor, Florida State and Butler.