Receiver Marqise Lee and tight end Xavier Grimble completed most drills Wednesday, and interim Coach Ed Orgeron said the juniors were probable for Friday night's Pac-12 Conference game at Corvallis, Ore.
Lee reinjured his left knee against Notre Dame on Oct. 19 and sat out last week's victory over Utah.
The reigning Biletnikoff Award winner completed the majority of Wednesday's 90-minute workout, which was devoid of contact.
Lee did not participate in team workouts Monday or Tuesday. Asked if seeing Lee running around brightened the mood at practice, Orgeron said, "It brightens mine. I didn't ask them if it brightens theirs, but it sure brightens mine."
Lee finished fourth in Heisman Trophy voting last season and began training camp regarded as one of the frontrunners to win the award.
But the All-American suffered a shoulder injury during training camp and then struggled with timing and drops during the first two games as Cody Kessler and Max Wittek alternated at quarterback.
Lee injured his left knee returning a punt against Arizona State on Sept. 28 and sat out the next game against Arizona.
He has a team-leading 32 catches in six games, but has scored only one touchdown.
"We'd love to have him back," Kessler said earlier this week.
Grimble suffered an ankle injury early in the Trojans' loss at Notre Dame and joined injured scholarship tight ends Randall Telfer and Jalen Cope-Fitzpatrick on the sideline against Utah.
Walk-on tight ends Chris Willson and Nate Guertler are expected to play again Friday, but Grimble's return would give Kessler another proven pass-catcher to go with Lee and receivers Darreus Rogers, De'Von Flournoy and Victor Blackwell.
Grimble has 10 receptions, one for a touchdown.
Oregon State receiver Brandin Cooks has 85 receptions, including 13 for touchdowns, but he is not limited to the passing game.
The junior also has rushed for 134 yards and two touchdowns.
Cooks also returns punts.
USC cornerback Kevon Seymour said this week that he anticipated being tested by quarterback Sean Mannion and Cooks.
But the Trojans are expected to employ a collective effort to control Cooks, who played at Stockton Lincoln High, the same school that produced Trojans tailback Justin Davis.
"Everybody's going to have their chance," Orgeron said.
The Trojans will have a walkthrough on campus Thursday before departing for Oregon…. Walk-on safety Adrian Johnson is the only player from Oregon on USC's roster. Oregon State has 28 players from Southland high schools…. Mike Summers, USC's offensive line coach, coached at Oregon State from 1991 to 1995…. Asked if he would dress up in a costume for Halloween, Orgeron said, "I quit doing that when I was about 5."