Wesley sparked the Trojans early with 13 first-half points, but it was Terrell who ignited the Trojans (10-13, 5-5 Pac 12) when they needed it most. Terrell scored all 12 of his points during a 10-minute stretch of the second half. His 3-pointer with 5:26 left put USC up 56-53, and the Trojans held the lead the rest of the way.
Ari Stewart added 11 points for USC, and Jio Fontan had 10 points and a game-high 11 assists.
Washington State's Brock Motum, who began the night ranked third in the Pac-12 averaging 18.3 points per game, scored 15 points on 6-of-16 shooting. DaVonte Lacy led all scorers with 21 points and his backcourt mate Mike Ladd had 16 for the Cougars (11-12, 2-8).
USC scored two quick buckets to start the second half to take a 34-33 lead, but Washington State responded with an 8-0 run to take its biggest lead of the game at 41-34. The Trojans, though, took advantage of Motum's uncharacteristically poor shooting night and managed to regain the lead.
Terrell was good on 3-pointers on consecutive trips down the court for the Trojans, who went up 49-47 with 7:45 to play. He hit his third 3 at the 5:26 mark to give USC the lead for good, but fouled out soon after.
USC forged ahead early in the game behind Wesley, who led all scorers with 13 first-half points. Stewart added eight points for the Trojans in the opening 20 minutes, including five points on consecutive possessions midway through the half that gave USC its biggest lead of the half, 21-14.
The Cougars, though, responded with a 19-7 run behind Lacy and Ladd to take a 33-28 lead. Lacy (nine points) and Ladd (eight points) led the way offensively for the Cougars, who made 6 of 12 3-pointers in the opening half.
The Trojans got to within 33-30 at the half when Wesley scored on a breakaway layup at the halftime buzzer.
Motum was held to six points in the first half and did not have a rebound.