A quartet of true freshmen pass-catchers trotted onto the Coliseum field around noon Saturday, taking their places to either flank of USC’s far-older quarterback. None of the four — neither Trent Mosley, nor Kayden Dixon-Wyatt nor Tron Baker or Mark Bowman — had played in a college football game. But the significance of their presence, on the first play of the first week of an especially critical campaign for USC and its coach, Lincoln Riley, was no small thing.

This USC season, if only by sheer numbers, is sure to be defined by how fast its freshmen can grow up, which, after Saturday’s season-opening, 42-26 win over San José State, might not sound so bad after all.

“It certainly wasn’t flawless,” Riley said, “but it was pretty damn good.”

First impressions, of course, can only say so much. With redshirts no longer a concern, Riley had promised to acclimate as many young players as possible. He stuck to a mostly conservative play script, leaning on the run and relying primarily on short passes through the air. Still, USC tallied more than 500 total yards in an otherwise ho-hum debut, with star quarterback Jayden Maiava completing 25 of 29 passes for 286 yards and three total touchdowns.

However, there were also plenty of glimpses that suggest the kids will be all right.

The most memorable came from Mosley, who took off with his first-ever collegiate punt and ping-ponged his way down the field, refusing to go down until he gained 41 yards.

It was just the start for the former Santa Margarita High standout. In the second quarter, Mosley caught a pass over the middle and broke three tackles for 33 yards. In the third, he burst open in the red zone and reeled in a 14-yard touchdown. He finished with seven catches for 118 yards and a touchdown, becoming the first Power Four freshman receiver to meet those marks in a debut since Purdue’s Rondale Moore in 2018.

“That kid moves differently,” running back King Miller said. “I mean, he’s special.”

There were standout moments for other members of the Trojans’ 2026 class, too. Defensive end Luke Wafle looked unblockable at times off the edge. Dixon-Wyatt dusted his defender off the line to catch a red-zone slant for a score. And quarterback-of-the-future Jonas Williams led a seamless fourth-quarter scoring drive.

USC wide receiver Trent Mosley breaks a tackle by San José State linebacker John Norwood.

USC wide receiver Trent Mosley breaks a tackle by San José State linebacker John Norwood during the first quarter Saturday.

(Ronaldo Bolanos / Los Angeles Times)

“They came out here and let it rip,” Riley said. “They all affected the game.”

But arguably the most encouraging results for USC came on the defensive end, where, for one half at least, Gary Patterson’s unit stood strong in his debut as Trojans defensive coordinator.

USC didn’t allow the Spartans to score until midway through the third quarter, when they opted for a field goal, down four touchdowns, just to wipe the zero off the scoreboard. San José State added another score after that, albeit long after USC’s starters had been replaced.

The defense held San José State to just 102 yards in the first half. It also gave up just 93 yards on the ground.

But when it let up late, the performance of Patterson’s defense took a serious downturn.

“When you start scoring a bunch of points and start laying up a little bit, that’s when things can go south,” defensive tackle Jide Abasiri said.

With mostly second- and third-stringers in for USC, San José State averaged 8.4 yards per play in the second half. Which didn’t leave Riley — or anyone — feeling great about the backups on defense.

“We’re going to need the depth of this roster,” Riley said, “and we obviously challenged that in the fourth quarter, and obviously didn’t respond the way we wanted.”

USC was at its best early, even with its fleet of freshmen needing time to find their footing. The Trojans immediately ripped off a 13-play touchdown drive to start the game. Fans were still filing in, braving 90-degree heat with novelty beer swords in hand, as Maiava moved USC methodically down the field, punching in a one-yard keeper for an early score.

A fourth-down stop at the goal line gave San José State a brief respite from USC piling on points. But Wafle, the five-star pass rusher, nearly added to the scoreboard anyway, when he slipped past the Spartans’ right tackle on third down, blew up the Spartan running back, and came up a split second short of a safety.

USC quarterback Jayden Maiava, right, hands off the ball to running back Riley Wormley.

USC quarterback Jayden Maiava, right, hands off the ball to running back Riley Wormley during the second quarter Saturday.

(Ronaldo Bolanos / Los Angeles Times)

USC still turned the sterling field position into points. While Waymond Jordan and Miller did most of the damage on the ground, combining for 111 yards, redshirt freshman Riley Wormley was the first USC running back to score. He was one of five to see work Saturday.

Miller led the way, with 63 yards. And he added his touchdown later, just before the half, as the Trojans took a 28-0 lead into the locker room.

San José State played USC a lot closer after that, actually outscoring the Trojans 26-14 in the second half.

The finish was enough to leave Patterson feeling a bit frustrated after his first game as USC’s defensive coordinator. But as far as first impressions go, Riley said, there was a lot to be happy about, too.

“I take it for what it is, right?” Riley said. “You don’t hide behind the fact that the fourth quarter wasn’t good enough. But I’m also not going to pretend we didn’t dominate that game through three quarters.”