LOS ANGELES — JuJu Watkins lay on the court, surrounded by her teammates, the final buzzer having faded.

The freshman sensation was cramping after scoring 32 points in No. 9 USC’s 73-65 victory over second-ranked UCLA. A trainer used a handheld massage gun on Watkins’ legs. She couldn’t stop smiling and laughing after anticipation had kept her awake the night before.

“She just goes all-out all the time,” USC coach Lindsay Gottlieb said.

Watkins and the Trojans sent the Bruins to their first loss of the season Sunday, leaving No. 1 South Carolina as the nation’s lone undefeated team.

“As a team we just were just so eager on defense,” Watkins said. “I fed off my teammates’ energy. You just want to be a part of that. On the defensive end, we played a great game. The whole team did it.”

It was Watkins’ sixth 30-point game of the season and first since Dec. 3 for the Trojans (13-1, 3-1 Pac-12), who extended their home winning streak to 17 games.

“I felt like this was going to happen,” Gottlieb said. “Our preparation and mentality was going to give us a chance to win the game.”

McKenzie Forbes added 18 points as the Trojans ended a nine-game skid against their crosstown rival. UCLA (14-1, 3-1) won 71-64 two weeks ago at Pauley Pavilion in front of a record crowd of 13,659 in the schools’ first meeting of top-10 teams this season.

“We showed so much what we’re capable of, not just to fans but to ourselves,” Forbes said.

Charisma Osborne led the Bruins with 25 points, all in the second half in front of a sellout crowd of 10,258 at Galen Center. After feeling sick at halftime, the fifth-year player hit a layup late in the third quarter that gave her 2,000 career points. Lauren Betts, UCLA’s leading scorer and rebounder, was held to 10 after not starting for the first time this season after being sick during the week.

“We were just trying to keep fighting, trying to get to the basket,” Osborne said. “We kept giving up buckets and we couldn’t get stops.”

All five of UCLA’s starters were in foul trouble, with Londynn Jones, Kiki Rice and Lina Sontag fouling out in the fourth.

Watkins was just 8-of-22 from the field and missed all six of her 3-point attempts, but she went 16-of-16 from the free throw line and had 10 rebounds.

“She’s going to score,” UCLA coach Cori Close said, “but we didn’t execute what we said we were going to do and we didn’t have each other’s back and you get caught.”

Forbes’ 3-pointer kept USC ahead 60-48 in the fourth.

But the Bruins ran off nine straight points, capped by Jones’ 3-pointer, to get to 63-59.

Watkins hit a jumper and Taylor Bigby scored for USC. Jones’ layup drew the Bruins within five points.

Jones missed a 3-pointer and Angela Dugalic missed a layup in the final 14 seconds.

The Bruins outscored USC 23-17 in the third quarter, getting 13 points by Osborne, to close to 51-42. Watkins picked up two quick fouls early but scored 10 points.

USC was missing starting center Rayah Marshall (13 points and 10.5 rebounds) and reserve Aaliyah Gayles, who were both sick.

The Trojans used runs of 11-0 in the first quarter and 15-0 in the second to lead 34-19 at halftime. Twice Watkins got her own offensive rebound and scored despite defensive pressure in the paint.

Before Watkins got going offensively, Harvard transfer Forbes hit back-to-back 3-pointers to power the Trojans’ first-quarter run.

The Bruins committed 15 turnovers that led to 16 points for the Trojans in the first half when UCLA starters Jones, Osborne and Dugalic were scoreless.

Among the celebs on hand were rappers Chris Brown and USC graduate Saweetie, Candace Parker and Hall of Famer Cheryl Miller.