Ryan Kartje (LA Times)  —  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 ever played in a college football game. But the significance of their presence, on the first play 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.

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 a mostly ho-hum debut, with star quarterback Jayden Maiava completing 25 of 29 passes for 286 yards and two touchdowns, plus a one-yd rushing score.

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.

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 WR Trent Mosley breaks a tackle by SJS LB John Norwood during the first quarter Saturday. (Ronaldo Bolanos / LAT)

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 would add another score after that, albeit long after USC’s starters had been replaced.

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 QB Jayden Maiava hands off the ball to RB Riley Wormley during the second quarter Saturday. (Ronaldo Bolanos / LAT)

USC still turned the sterling field position into points. While Waymond Jordan and King 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 (8) 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.

It was the sort of lacking conclusion for USC that probably left both Riley and Patterson wanting a bit more. And yet another slow finish has some USC fans predicting trouble ahead against tougher teams. But as far as first impressions go, it would do the job for one Saturday at least.