Elijah Stewart had 18 points and USC won their fourth straight with a 74-67 victory over Oregon State on Saturday night.
Jordan Usher added 14 points for USC (15-6, 6-2 Pac-12), who have won four straight in the series against the Beavers (11-8, 3-4).
With their victory over Oregon on Thursday, the Trojans won both games in the state of Oregon for the first time since the 2008 season.
Tres Tinkle had 21 points and seven rebounds for the Beavers. Tinkle is the only player in the Pac-12 that has reached double figures in every game this season.
The Trojans fell behind in the second half by as many as eight points, but rallied with just over six minutes left when consecutive 3-pointers from Usher gave the Trojans a 58-54 lead. Jordan McLaughlin added a layup and a 3-point play before an 18-0 run was capped by free throws from Stewart to put USC up 65-54.
The Beavers closed within 69-63 on Stephen Thompson Jr.'s jumper with 1:48 left, but got no closer. Thompson finished with 16 points.
Tinkle had 16 points on Thursday night and the Beavers snapped a two-game losing streak with a 69-63 victory over UCLA.
McLaughlin scored the Trojans' last eight points, including six consecutive free throws, to help hold off Oregon for a 75-70 victory earlier Thursday night.
The Trojans made six of their first seven shots and led the Beavers 14-7. Jonah Matthews' 3-pointer gave USC a 23-16 lead as the Beavers struggled to find momentum. Each time Oregon State looked like it was mounting a rally, the Trojans responded.
But the Beavers pulled closer at the end of the half when Nick Rakocevic was called for a personal foul and USC coach Andy Enfield got a technical. Tinkle made both shots, then added two free throws to tie it at 33.
McLaughlin had a pair of free throws for the Trojans go into halftime up 35-33. Tinkle led all scorers with 14 points.
Thompson hit a 3-pointer to give the Beavers the lead at the start of the second half. Tinkle's layup extended the lead to 41-37, then his dunk pushed it to 45-37 and the momentum had fully shifted to Oregon State.
Chimezie Metu's free throws got the Trojans within 49-47 with 9:30 left. But Thompson had a layup and little brother Ethan Thompson added a 3-pointer to extend it for the Beavers again.
But the Trojans stayed close, and Usher's 3-pointer with 6:16 to go gave the Trojans back the lead.
The Beavers went into the game holding opponents to 68.4 points a game to lead the Pac-12.