Caleb Williams, the reigning Heisman winner, scored on a two-point conversion to start the third overtime as No. 9 USC survived a wild night to beat Arizona 43-41 in triple overtime on Saturday night in Los Angeles.

The Trojans (6-0, 4-0 Pac-12) had their hands full from the start, trailing 17-0 early in the second quarter and failing to win the game on the final play of regulation when a high snap led to a blocked 25-yard field goal attempt.

The winning points came on a crazy play, with most of the offensive line shifted way to the left side of the field. Williams took the snap, rolled right and scrambled to the corner, barely extending the ball over the pylon. Arizona (3-3, 1-2) then was stopped on its two-point try as USC's Mason Cobb tackled DJ Williams on a toss to the left.

Caleb Williams completed just 14 of 25 passes for 219 yards with a touchdown, but he helped will his team to victory, rushing for three touchdowns, including an 18-yarder to start the overtime periods.

Arizona's Noah Fifita, making his second career start, completed 25 of 35 passes for 302 yards and five touchdowns, including two in the overtime periods to Jacob Cowing. Both teams missed two-point conversions in the second overtime.

USC, which entered with the nation's top-scoring offense (53.6 points per game), was outgained 505-351 but held a 28-20 lead in the fourth quarter. Arizona tied the score when Fifita connected with Cowing on a 3-yard touchdown pass on fourth down, followed by a two-conversion throw to Tetairoa McMillan with 8:17 left.

The Wildcats had a chance to take the lead with 2:08 left, but Tyler Loop missed a 50-yard field goal.

The Trojans, who trailed in a game for the first time this season, took their first lead at 21-20 with 5:44 to go in the third quarter after MarShawn Lloyd scored on a 9-yard run. Arizona helped the Trojans with a fourth-down pass interference penalty and a third-down roughing-the-passer infraction during the 75-yard drive.

USC padded its lead early in the fourth quarter when Williams, initially stopped on a quarterback sneak from the 1, squirmed through a tackle and reached the ball across the goal line for a 28-20 advantage.

--Field Level Media