Isaiah Thomas, the conference's leading freshman scorer with 16.3 points per game, was held to a season-low four points on 2-for-7 shooting for the Huskies. Justin Dentmon had eight points and Venoy Overton added seven.
Daniel Hackett and Dwight Lewis scored 11 points each for the Trojans (16-10, 7-7), who led by four with 5:52 left and scored just one point the rest of the way.
Pondexter's layup with 4:58 left tied the score at 50, and his turnaround jumper 22 seconds later gave Washington the lead for good.
USC took an 18-9 lead on Lewis' fastbreak layup with 14:12 left in the first half. Lewis took off after intercepting a pass from Overton that was intended for Washington's Dentmon and took it down the court.
Overton had seven points during an 18-2 run that helped the Huskies take a 31-28 lead at halftime.
Dentmon, who averages 15.8 ppg, had four points and was 1-for-8 from the field in the first half while Thomas went 0-for-3.
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