SEATTLE -- Lia Galdeira scored 28 points, Tia Presley added 19 including a huge 3-pointer with 1:21 remaining as the shot clock expired, and Washington State upset No. 20 Cal 91-83 on Friday night in the Pac-12 tournament quarterfinals.

The Cougars used a 15-4 run midway through the second half to take control, then held off Cal's charge in the closing minutes. Washington State (17-15) snapped a five-game losing streak to Cal, the No. 2 seed in the conference tourney, and improved to 4-5 this year against ranked opponents.

The Cougars would likely need to win the conference tournament to reach the NCAAs. They scored a tournament-record 107 points in beating Oregon in the opening round Thursday.

Reshanda Grey led Cal (21-9) with 26 points, but second-leading scorer Brittany Boyd finished with nine points and fouled out with 6 minutes left.

Sage Romberg added 16 points for the Cougars and Mariah Cooks had 12 important points off the bench, including eight during the Cougars' decisive run. Washington State will face either Oregon State or Utah in the semifinals Saturday night.

Leading 63-59, the Cougars scored six straight points to take their biggest lead of the night at 69-59 with 10:25 left. Cooks scored on consecutive possessions down low, and Galdeira hit a turnaround fadeaway from the low block to cap the spurt.

But Washington State's charge didn't stop. Cal's Gennifer Brandon hit an open jumper out of a timeout, but Cooks scored again, Taylor Edmondson hit a 3 in transition and Shalie Dheensaw used every part of the rim on a 10-foot jumper for a 76-61 lead with 8:21 left.

Cal got back within 80-69, but Boyd fouled out after picking up two fouls more than 70 feet from the basket less than 35 seconds apart. She checked out with 6:21 left and the Bears trailing by 11. Even with their leader out, the Bears chipped away, coupled with poor clock management by Washington State.

Brandon's three-point play with 1:55 left pulled Cal within 84-78, but Presley hit a corner 3 with 1:21 left as the shot clock expired to push the lead back to nine and drew a fist pump from coach June Daugherty.

The Cougars avenged a 70-65 overtime loss at Cal a week ago. Brandon finished with 20 points off the bench for Cal, which has lost two straight. Afure Jemerigbe added 16.