TUCSON, Ariz. -- No. 4 Arizona will be riding a wave of momentum heading into a Saturday showdown against No. 5 UCLA.

Guard Allonzo Trier scored a season-high 25 points for the hot-shooting Wildcats, who stayed in control of the Pac-12 race by beating USC 90-77 on Thursday night.

Arizona (26-3, 15-1 Pac-12) improved its conference lead to one game over Oregon, which won at Cal on Wednesday night. USC (21-7, 8-7) went winless in a three-game conference gauntlet -- Oregon, at UCLA and at Arizona.

"We have to rest up and make sure our minds are prepared," Trier said of the Saturday matchup, which will be only the seventh matchup of top-5 teams in conference history. "It's going to be a great battle. We had a great war with them the first time. We know how much this game means. We will be prepared."

Arizona won the first meeting against the Bruins 96-85 in Pauley Pavilion on Jan. 21.

On Thursday, Trier hit 7 of 11 shots, including 4 of 6 from 3-point range. The sophomore was playing in his 10th game of the season following an NCAA suspension for testing positive for a performance-enhancing substance.

The Wildcats shot 50.8 percent from the field, 55 percent from 3-point range and 88.2 percent from the foul line.

"We just couldn't get key stops down the stretch for periods of the second half," USC coach Andy Enfield said. "Give Arizona credit. They got the ball inside and they made 11 threes. With their inside-outside punch ... they are tough to beat."

USC shot 52.9 percent and posted the highest point total by an visitor at McKale Center this season.

"We did our job offensively," Enfield said, "but Arizona just played too well offensively in their own right for us to beat them."

Arizona guard Rawle Alkins scored 12 points in only 16 minutes -- making all five of his shots from the field -- as he came off the bench for the first time this season.

Wildcats starting point guard Kadeem Allen returned from a finger injury on his right hand, and coach Sean Miller paired him in the lineup with another point guard, Parker Jackson-Cartwright. The pair combined for 18 points, eight rebounds, seven assists and five steals.

USC power forward Bennie Boatwright scored 23 points, making 3 of 7 shots from 3-point range. Trojans center Chimezie Metu had 15 points and 12 rebounds. Despite the loss, USC remains in good shape for an at-large bid to the NCAA Tournament.

"USC is a really good team," Miller said. "They have an abundance of talented players and a really good coach. We had plenty of breakdowns, and that is to USC's credit."

It was a five-point game until Alkins hit a layup with 12:52 to go, beginning a stretch in which the Wildcats hit six consecutive shots to build the lead to 71-55. The Trojans hung around long enough to cut the deficit to 80-73 with 1:49 to go on Boatwright's two free throws.

Arizona forward Lauri Markkanen responded with a driving layup, and then, on the other end, the 5-foot-11 Jackson-Cartwright blocked a driving layup by the 6-10 Boatwright to help seal the victory.

"We're going to need a better effort, frankly, over what we did on the defensive end," Arizona assistant coach Mark Phelps said of the looming matchup against high-scoring UCLA. "That's the key -- guarding guys off the dribble, getting back in transition."

NOTES: Arizona won 70 of its past 71 games at home. ... USC G Elijah Stewart received a technical foul for hanging on the rim after a running two-handed dunk with 9:09 to go in the first half. ... Arizona F Lauri Markkanen's father, Pekka, traveled from Finland to attend the game. Pekka played at the University of Kansas for a year. ... Arizona G Kadeem Allen, who missed two games last week, played with a splint on his dislocated right pinky finger. ... ESPN's "College GameDay" program will broadcast from McKale Center on Saturday. ... USC plays at Arizona State on Sunday.