LOS ANGELES — Coach Sean Miller knew Arizona didn't have its act together on defense. After getting swept in Los Angeles, maybe the seventh-ranked Wildcats will finally believe him.
Elijah Stewart scored a career-high 27 points, including the go-ahead free throws with 22 seconds left in the fourth overtime, helping Southern California to a 103-101 win on Saturday night.
Arizona's Gabe York dribbled around as the clock wound down and had the ball smacked away by Jordan McLaughlin before the Wildcats recovered only to see Kadeem Allen's 3-point attempt fall short at the buzzer, ending the first quadruple OT game in school history.
"In many ways this trip will have great meaning for our future," Miller said. "It's good for our guys to see how we feel when we're not a good defensive team."
Julian Jacobs added 18 points, and McLaughlin and Nikola Jovanovic had 17 each for the Trojans (14-3, 3-1 Pac-12), who hung in and hung on after blowing a 12-point lead with 5 1/2 minutes to go in regulation.
Allonzo Trier scored 25 points and York added 21 for the Wildcats (13-3, 1-2). They lost by three points at UCLA on Thursday.
"We're not good enough," a downcast York said. "We got to all look at ourselves in the mirror, especially me. I didn't answer the bell for my team in both games."
Arizona's Ryan Anderson had his streak of five straight games with double-doubles snapped when he was held to a season-low five points on just seven shots.
The Wildcats allowed USC to shoot 64 percent in the first half and then held the Trojans to 31 percent in the second half.
"In the first half you'd say we were really bad," Miller said. "In the second half and four overtimes, you'd say our defense is outstanding. We have done that a number of times this year."
In the fourth OT, Trier's basket gave Arizona a 99-97 lead. The Trojans got two free throws from Jovanovic and Stewart scored on a layup to make it 101-99. Kaleb Tarczewski tied it for the last time on a pair of free throws before Stewart got fouled and made the winning free throws.
The Wildcats trailed by 12 points when they closed regulation on a 14-2 run to tie the game at 73-all. Allen's layup forced overtime after USC briefly regained the lead on a layup by Jovanovic.
Arizona led 77-75 in the first OT before the Trojans made four straight free throws to take a two-point lead. Tarczewski's tip-in tied it at 79-all to force the second OT.
Tarczewski's jumper tied the game in the second extra session before York's 3-pointer gave Arizona an 84-81 lead. But the big man's offensive foul gave the Trojans possession and they scored on Stewart's layup to take an 85-84 lead.
Tarczewski fouled Jovanovic, who missed the first and made the second.
York made a pair of free throws for an 86-all tie. Trier stole the ball off a bad pass by Jacobs, but didn't have enough time to get off a shot and the teams went to a third OT.
The Wildcats led by four before USC scored six straight points to go up 95-93. York's layup tied it at 95-all, forcing the last OT.
Arizona: The Wildcats have scored 80 or more points in eight straight games. ... They dropped to 34-13 in games following a loss under Miller. ... They are 7-9 in the second game of the Los Angeles trip since 2000, and 3-3 since Miller took over in 2009.
Southern California: The Trojans completed a sweep of the Arizona schools, having beaten Arizona State 75-65 on Thursday. ... Former USC star and current Lakers player Nick Young attended.
Arizona: Hosts Washington Thursday.
Southern California: At crosstown rival UCLA on Wednesday.