The Huskies, 19-10 overall and 13-4 in the conference standings, put the game out of reach with a 17-2 scoring burst that began midway through the second half. They stretched the lead to 22 points at 82-60 with seven minutes remaining.
The Huskies trail first-place Arizona by one game.
The Cardinal, led by freshman Todd Lichti with a game-high 24 points, fell to 14-15 overall and 8-9 in Pac-10 play.
The Washington scoring burst was punctuated by a five-minute stretch during which Al Moscatel inadvertently elbowed Stanford's John Paye in the nose, setting off a demonstration by the Stanford bench and the crowd.
After the game, doctors at University Hospital reported Paye's nose was broken and required surgery. Paye is the starting quarterback on the Stanford football team.
Chris Welp, 7-foot junior center and Pac-10 Player of the Year, scored on a 15-foot jumper off a fast break after the Moscatel-Paye collision to stretch the lead to nine.
Welp, who scored his season-average 19 points, pulled down a game-high 14 rebounds, including 10 in the first half.
Washington State 81, California 78--Joe Wallace scored 21 points, including six in overtime, to lead the Cougars to victory at Pullman, Wash.
California fell to 18-9 overall and 10-7 in the Pac-10. The Cougars climbed to 14-16 and 7-10.
The Bears forced the game into overtime when Dave Butler, a 52% free-throw shooter, hit two free throws with one second left to tie the score at 67-67.