Woolridge hit five 3-pointers and Motum three, helping the Cougars (13-18 overall, 4-14 Pacific-12 Conference) to their first winning streak in conference play this season with a sweep of the Los Angeles schools. Washington State defeated UCLA on Wednesday.
“Considering where we were with our record, to come back home and play two good games does a lot for our confidence, and it was the right time to do it,” Cougars coach Ken Bone said. “If we didn’t do it this weekend, it would never happen.”
Washington State earned the 11th seed in the conference tournament and plays No. 6 seed Washington at 8:30 p.m. Wednesday in Las Vegas.
T.J. Terrell had 18 points for the Trojans (14-17, 9-9). He was the only player in double figures for USC, which struggled from the field (19 for 56) and behind the arc (4 for 24).
USC is seeded seventh in the tournament and faces No. 10 seed Utah on Wednesday.
The Cougars never trailed and raced to a 22-point lead in the first half. Motum had 21 of his points before halftime.
The Trojans opened up the second half with an 18-4 run and cut the deficit to five, 45-40.
Washington State put the game out of reach when Woolridge hit four consecutive 3-pointers to make it 66-46 with 4:42 remaining.
“They have improved a great deal since the last time we played; there is a big difference in how they execute their offense and how they play on defense,” USC interim coach Bob Cantu said.
The Cougars outrebounded the Trojans 45-34 and committed only five turnovers.
At No. 18 Arizona 73, Arizona State 58: Nick Johnson scored 17 points, Solomon Hill added 12 in his final home game and the No. 18 Wildcats (24-6, 12-6) earned a first-round bye in next week’s Pac-12 tournament with a rout over the Sun Devils (20-11, 9-9).
Arizona built a 15-point lead in the first half and answered a big second-half run by Arizona State with one of its own.
The Sun Devils pulled within five in the second half, but had trouble holding onto the ball, their 17 turnovers leading to 21 points for the Wildcats.
At Utah 72, No. 19 Oregon 62: Jason Washburn had 20 points and 13 rebounds, and Jarred DuBois added 15 points and several key baskets down the stretch to propel the Utes (13-17, 5-13) over the No. 19 Ducks (23-8, 12-6).
Jordan Loveridge and Brandon Taylor chipped in 14 points apiece for Utah, which forced Oregon to commit 15 turnovers and scored 21 points off those miscues.
E.J. Singler had 21 points and seven rebounds to lead the Ducks, who finished in a second-place tie behind UCLA for the Pac-12 regular-season championship.
Oregon State 64, at Colorado 58: Eric Moreland scored 17 points and Roberto Nelson added 15, helping the Beavers (14-17, 4-14) snap a five-game skid by holding off the Buffaloes (20-10, 10-8).
It was the first win in Boulder, Colo., for Oregon State, which was 0-6 before Nelson closed out a tight game on a layup with 15 seconds remaining, sending the Buffaloes crowd heading for the exits.
Spencer Dinwiddie had 18 points for Colorado, which was attempting to tie the school record for regular season wins.