The No. 8 seed Trojans (16-16) started slowly, but went on 18-2 runs in each half to earn a spot in Thursday’s quarterfinals against top-seeded Washington.
Arizona’s difficult season may have come to an end with its first opening-round Pac-12 exit since 2010.
The two-time defending champion Wildcats (17-15) continued to be embroiled in a recruiting scandal and struggled on the court, punctuated by their lopsided loss to the Trojans.
Unless Arizona gets an invite to a smaller tournament, it will not play a postseason game for the first time since 1983-84, Lute Olson’s first year as coach.
The Wildcats dug a big early hole, fought back by halftime and fell behind by double digits midway through the second half. Ryan Luther scored 16 points and Brandon Williams 13 for the Wildcats, who went 5 for 22 from the 3-point arc.
The Trojans closed out a disappointing regular season with four straight losses and seven in nine games.
Arizona ended with a similar thud, losing to rival Arizona State for its ninth loss in 10 games.
USC won the teams’ lone meeting this season, rolling over the Wildcats 80-57 at home.
The Trojans got the Pac-12 tournament off to a slow start before going on an 18-2 run to go up 23-12.
But instead of racing off to another rout, USC started sputtering, allowing Arizona back in it. The Wildcats went on a late 13-3 run and tied it at 40-all by halftime. Arizona made 13 of 26 first-half shots after shooting 28 percent the first game against USC.
USC took control midway through the second half, using with another 18-2 run to go up 63-45.
USC has another chance to extend its season after shutting down Arizona
Arizona was out of sorts for long stretches in each half and could face a long offseason if it doesn’t get a postseason bid.
USC moves on to face top-seeded Washington the quarterfinals.
Arizona waits to see if it will get an invite to a smaller postseason tournament.