LOS ANGELES — Elijah Stewart 17 scored and Bennie Boatwright added 13 points to lead Southern California to an 89-71 victory over Washington State in a Pac-12 game on Sunday night. After starting the season 6-0, WSU (8-6, 0-2) has lost six of its last eight games. The Cougars have lost five straight to USC (10-5, 1-1). Nick Rakocevic scored 12 points and had nine rebounds, Jonah Mathews added 11 points and Jordan Usher scored 10 for the Trojans.