LOS ANGELES — O.J. Mayo disappeared in the opening minutes of Southern California's game against Oregon State. He returned in short order, though, and led the Trojans to an important weekend sweep.

LOS ANGELES — O.J. Mayo disappeared in the opening minutes of Southern California's game against Oregon State. He returned in short order, though, and led the Trojans to an important weekend sweep.

Mayo was one of four players in double figures with 21 points and USC won 81-53 Saturday night, keeping the hapless Beavers winless in the Pac-10.

He had to leave the court after stepping on the back of Lathen Wallace's shoe and tweaking his left Achilles' tendon. "I iced it and it should be ready to go Monday," Mayo said.

He had four 3-pointers, giving him 66 and moving him past Gabe Pruitt as the most prolific freshman long-range shooter in USC history. Mayo was coming off a 32-point effort in an 81-75 victory over Oregon on Thursday.

"Everyone has a bad game," he said. "More importantly, our team regrouped and won two games."

The Trojans (17-9, 8-6 Pac-10) needed the weekend sweep to keep their NCAA tournament hopes alive. They had to rally in both halves to beat Oregon, but Saturday's game was virtually over before it began.

"If we keep winning, we will (make the tournament)," coach Tim Floyd said. "I don't think we're there yet. A lot of people think 8-10 will get you in. We're not going to treat it that way."

Dwight Lewis added 14 points, Angelo Johnson 13, including a career-high four 3-pointers, and Taj Gibson 12 for the Trojans, who have won eight of 11. They earned their 17th victory for the first time in three consecutive seasons since 1991-93.

"This Pac-10 final stretch, we need every win," Gibson said. "It keeps us up there with the top four (teams). We just want to stay above .500."

The Beavers (6-21, 0-15) lost their 17th in a row and are on the verge of going winless in the Pac-10 with three games remaining.

Senior Marcel Jones and freshman Sean Carter were back in Oregon State's lineup after one-game suspensions for their involvement in verbal taunting against Washington last weekend.

Jones led the Beavers with 15 points and Calvin Haynes added 10. The team shot 34 percent for the game.

"It got away from us in a hurry," interim Oregon State coach Kevin Mouton said. "They shot 50 percent from 3-point range in the first half. We never got into the bonus, and they shot 24 free throws in the first half. You cannot let any team in the league shoot like that, especially from 3-point range, and expect it to be close."

Oregon State's 16 first-half points were the fewest by a USC opponent this season and the worst half of the season for the Beavers.

Johnson, one of USC's three freshmen starters, further stunned Oregon State by hitting three consecutive 3-pointers early in the second half, increasing the Trojans' lead to 34 points.

He has stepped up in the absence of guard Daniel Hackett, who is out indefinitely because of a stress fracture in his lower back and a partially torn oblique muscle.

Hackett said he practiced free throws before the game Saturday, the first day he was able to run despite still having soreness. He is scheduled to see a doctor Monday.

Mayo had a dominating stretch midway through the half. He scored and got out on a fastbreak, sending a behind-the-head pass to a trailing Lewis, who scored. Mayo dunked and then hit a 3-pointer to complete the 9-0 run and stretch the Trojans' lead to 67-30.

"At halftime, he (Floyd) didn't want us to lay down," Mayo said. "Sometimes it's hard not to turn the game into a performance with a big lead and the home crowd behind you."

It was USC's seventh straight win over the Beavers.