Arizona trailed by four at the half and went down by six early in the second half before getting out to an 8-0 run to take a brief lead. USC responded almost immediately and used a 15-3 run to build up a 10-point lead that they would never completely surrender.
Arizona cut it to two on a few occassions late but could not get any closer.
The Wildcats shot just 38.3% from the field and 28.6% from behind the arc.
The Trojans, who lost in the final seconds to UCLA last Saturday, have now beaten five ranked teams.
On the other hand the Wildcats have lost three of their last four after going on a 12-game win streak earlier in the season.
Things do not get any easier for the Wildcats as they have to face off against the No. 3 ranked Bruins.