USC receiver Juju Smith-Schuster hauls in a 25-yard touchdown pass in the fourth quarter of a game against Utah at the Coliseum on Oct. 24.(Robert Gauthier / Los Angeles Times)
USC linebacker Cameron Smith (35) intercepts a pass from Utah quarterback Travis Wilson during the second half of the Trojans’ 42-24 win over the previously unbeaten Utes.(Mark J. Terrill / Associated Press)
USC interim Coach Clay Helton shakes hands with Utah Coach Kyle Whittingham following the Trojans’ 42-24 victory over the Utes at the Coliseum on Oct. 24.(Mark J. Terrill / Associated Press)
USC linebacker Jabari Ruffin celebrates with his team after the Trojans’ 42-24 win over No. 3 Utah at the Coliseum on Oct. 24.(Mark J. Terrill / Associated Press)
USC linebacker Cameron Smith returns his third interception of Utah quarterback Travis Wilson during second half of a game at the Coliseum on Oct. 24.(Robert Gauthier / Los Angeles Times)
USC linebacker Cameron Smith celebrates after returning and interception for a touchdown against Utah during the second quarter of a game on Oct. 24 at the Coliseum.(Robert Gauthier / Los Angeles Times)
USC linebacker Cameron Smith returns an interception past the missed tackle of Utah quarterback Travis Wilson during a game on Oct. 24 at the Coliseum.(Robert Gauthier / Los Angeles Times)
USC defensive lineman Greg Townsend Jr. sacks Utah quarterback Travis Wilson during the first half of a game at the Coliseum on Oct. 24.(Robert Gauthier / Los Angeles Times)
USC fullback Soma Vainuku dives over the pile for a second quarter touchdown against Utah during a game at the Coliseum on Oct. 24.(Robert Gauthier / Los Angeles Times)
USC interim Coach Clay Helton signals touchdown after fullback Soma Vainuku scores in the second quarter of a game against Utah. USC beat No. 3 Utah, 42-24.(Robert Gauthier / Los Angeles Times)
USC running back Ronald Jones breaks free of Utah defensive back Marcus Williams to score a touchdown during a game on Oct. 24 at the Coliseum.(Robert Gauthier / Los Angeles Times)
USC quarterback Cody Kessler is sacked during a first quarter drive against Utah during a game on Oct. 24 at the Coliseum.(Robert Gauthier / Los Angeles Times)
USC quarterback Cody Kessler is sacked during the first quarter of a game against Utah on Oct. 24 at the Coliseum.(Robert Gauthier / Los Angeles Times)
USC running back Soma Vainuku scores on a one-yard touchdown run to tie the game, 14-14, during the second quarter of a game on Oct. 24.(Harry How / Getty Images)
Utah quarterback Travis Wilson scrambles out of the pocket during the second quarter of a game against USC at the Coliseum on Oct. 24.(Harry How / Getty Images)
Utah running back Bubba Poole scored on a two-yard run against USC during the first quarter of a game Oct. 24 at the Coliseum.(Harry How / Getty Images)
A cleaning crew member polishes seats hours before USC and Utah play at the Coliseum on Oct. 24.(Robert Gauthier / Los Angeles Times)
Cameron Smith stood in the middle of the Coliseum field on Saturday night looking like the picture of calm.
The freshman linebacker’s cardinal jersey was muddied, his full red beard scruffy and his shoulders were broad and straight after a game of frenetic and game-turning activity that carried USC to a convincing 42-24 victory over third-ranked Utah.
Smith intercepted three passes, including one he returned for a touchdown. “It’s hard to wrap my head around it,” the freshman said.
The same could be said of the Trojans’ convincing victory over a previously unbeaten Utah team that was regarded as perhaps the physically toughest in the Pac-12 Conference.
USC improved to 4-3 overall and 2-2 in the Pac-12 and stayed in the race for the South Division championship.
After losses to Washington and Notre Dame, Trojans players showed they were no longer reeling from the events surrounding the firing of Steve Sarkisian.
“It looked like a new team,” Smith said. “We just need to build on this.”
Smith was instrumental in giving interim Coach Clay Helton his first victory at the Coliseum, a win that perhaps kick-started Helton’s drive to become Sarkisian’s permanent replacement.
“Unbelievable,” Helton said of Smith’s performance. “He won the game for us.”
Trojans quarterback Cody Kessler concurred.
“Those picks,” he said, “that won us the game.”
It was a dose of redemption for the 6-foot-2, 245-pound Smith, who saw two certain interceptions slip through his fingers earlier this season. For the last three weeks, he has toiled every day at practice catching balls shot out from a machine.
It paid off against Utah (6-1, 3-1).
“I just saw the ball coming my way and just tried to make an impact,” said Smith, who also made a team-best nine tackles.
Smith, who attended Granite Bay High near Sacramento, was part of a recruiting class that included highly regarded linebackers Osa Masina, Porter Gustin and John Houston Jr.
His first interception Saturday came in the second quarter with the Trojans trailing, 14-7.
Smith picked off Utah quarterback Travis Wilson’s pass and returned it 41 yards to the Utah four. Four plays later, fullback Soma Vainuku scored to tie the score.
Later in the quarter, Utah faced fourth and two when Smith intercepted another pass at USC’s 46 and rambled 54 yards to the end zone to put USC ahead, 28-14.
Smith got his third interception with just under nine minutes left, and he returned it 27 yards.
“My eyes got big and I was thinking ‘Oh my gosh, not again,’” he said.
Smith became the first USC player to intercept three passes in a game since Jason Oliver in 1991 against Penn State.
“I just read [Wilson’s] eyes a couple times and got lucky,” he said.
USC went into the game in danger of losing a third consecutive regular-season game for the first time since 2001.
Las Vegas oddsmakers saw something in the Trojans — or perhaps in Utah — that others had not. USC opened as a three-point favorite and played much of the night with confidence befitting an unbeaten team.
The Trojans matched the aggressive Utes punch for punch, took advantage of turnovers and avoided the costly mistakes that plagued them against Washington and Notre Dame.
“Credit USC, they came to play today,” Utah linebacker Gionni Paul said. “Didn’t expect to get punched in the mouth like that. It was a reality check.”
The Trojans outgained the Utes, 380-353, and USC’s defense shut down Utah running back Devontae Booker and quarterback Travis Wilson.
Booker, who came into the game averaging 130.5 yards a game, gained only 62 yards in 12 carries. Wilson passed for two touchdowns, but he could not avoid Smith and also had a Hail Mary intercepted by Su’a Cravens with two seconds left.
“We don’t like losing,” Cravens said. “The reason we came out and played like this is because we don’t like losing.”
USC led, 28-17, at halftime on touchdown runs by Justin Davis, Vainuku and Ronald Jones II, and Smith’s touchdown return.
The Trojans extended the lead in the third quarter with a long drive that Kessler finished with a fourth-down sneak.
The Trojans turned it into a rout in the fourth quarter when Kessler connected with receiver JuJu Smith-Schuster for a 25-yard touchdown.
“I want to thank these players — unbelievable resiliency that these guys have,” Helton said. “You can see guys continue to fight and continue to bond together.”
Follow Gary Klein on Twitter @LATimesKlein