Tyrone Wallace scored all of his game-high 17 points in the second half Sunday night to lead California to an 80-62 win over Washington State.
Ivan Rabb added 15 points for the Bears (19-8, 9-5 Pac-12 Conference), and Jabari Bird had 13.
California's victory, combined with USC's loss to Utah earlier in the day, moved the Bears past the Trojans into fourth place. The top four seeds in the Pac-12 tournament receive first-round byes.
Washington State's loss clinched the No. 12 seed for the Cougars (9-18, 1-14), who have lost 13 in a row.