LOS ANGELES >> Tim Lester is among the thousands of football men who became big fans of Sam Darnold last season.

Just 11 days after Darnold’s 453-yard, five-touchdown performance for Southern California in the last Rose Bowl, Lester got the head coaching job at Western Michigan — and Darnold became his first problem.

The No. 4 Trojans return from their Pasadena victory over Penn State to open a season of enormous expectations Sept. 2 at the Coliseum against Lester’s Broncos.

Darnold is back for his first full season as USC’s starting quarterback, with the Heisman Trophy and the Pac-12 title squarely in the sights of the gifted passer. Lester won’t be surprised if Darnold fulfills his enormous potential, but the former Western Michigan quarterback will do his best to delay that process by a week.

“I’ve always liked Sam, watching him as a guy who loves to watch quarterbacks play,” Lester said. “When they won the Rose Bowl and he walked off to the sideline like, ‘Ho hum,’ like it was just another day at the office, I already liked him. I loved him from that moment. I just liked the way he handled that situation. Little did I know we’d be playing him in eight months.”

A year after the Trojans began their season with a thrashing from Alabama and ended it with nine consecutive wins, they’ve taken on another significant challenge in their opener.

Western Michigan has 15 starters returning from the best season in school history, which included 13 victories and a Cotton Bowl appearance. But the Broncos also are rebuilding after the departures of head coach P.J. Fleck, longtime starting quarterback Zach Terrell and star receiver Corey Davis.

“They’re going to be a big challenge, even with the guys who left,” USC cornerback Iman Marshall said. “We’re going to be ready for a team that won 13 games last year.”

Here are more things to watch in the opener of the 125th season of USC football:

>> New targets: Darnold is back, but his top two receivers from last season are gone. USC is loaded with its usual blue chip talent at the position, and Rose Bowl star Deontay Burnett is Darnold’s probable No. 1 target, but coach Clay Helton has repeatedly cited the Trojans’ receivers as the area of his team with the most uncertainty.

Darnold feels more comfortable after a month of training camp.

“It’s just about time and spending more time and experiencing different things with them,” Darnold said. “Actually playing a game is going to be helpful for us in understanding who can play and who can’t.”

>> First start: Jon Wassink hasn’t played in a real game since his high school state final in Grand Rapids in 2014. He returns to face the vaunted Trojans at the Coliseum while replacing Terrell, the Campbell Trophy winner and top passer in school history.

Lester compares Wassink’s demeanor to Darnold’s laid-back vibe.

“I don’t think he’s going to let his nerves get in the way,” Lester said. “For him, it’s just going to be the speed. The speed of the game, the first time you go out there, is unlike anything you’re ever used to. Eventually it slows down for you.”

>> Heat Wave: The Coliseum is likely to be 95 degrees around kickoff, thanks to a week of high heat in Southern California.

Both teams will emphasize the importance of hydration and rotation.

“I don’t think it will be a huge deal as long as you have the depth to rotate, and we do,” Lester said.

>> Run First: With Wassink making his debut, the Broncos seem likely to run the ball with returning senior Jarvion Franklin, who already has 3,639 career yards and 41 touchdowns rushing.

Rasheem Green is the only returning starter on the Trojans’ defensive line.

>> High Stakes: Despite their preseason hype, the Trojans have a daunting September schedule. After Western Michigan, USC hosts Stanford and Texas, followed by a short-week trip to Washington State.

A slip-up against the solid Broncos could have ugly effects on another season of high expectations for a team that started 1-3 last season.