LOS ANGELES -- One of the defining moments last season under coach Lincoln Riley came on the road against Michigan during the program's first conference game as a member of the Big Ten. 

When push came to shove and Riley's team needed a stop to win the game, the Wolverines introduced their new conference foe to the "big boy" brand of football the Big Ten plays by scoring a 1-yard touchdown on fourth-and-goal in an eventual 27-24 win during the final minute.

That game proved to be a measuring stick for a USC program that had improved the nuts and bolts of its defense but still needed to shore up everywhere in the trenches. 

Just over a year after that result, the once bullied were the ones who did the bullying during a 31-13 statement win over No. 15 Michigan on Saturday. USC won in the trenches and racked up 489 yards of total offense -- including 224 on the ground despite not having its top two running backs (Waymond Jordan and Eli Sanders) for most of the game -- and recorded three sacks while allowing none. It was even more impressive considering USC did it with a makeshift offensive line because starters Kilian O'Connor and Elijah Paige were both ruled out.

"It says we are a tough ass, physical program," Riley said. "It's what it says. ... I don't think many offensive lines in the country would've been able to do (what we did) minus three starters. It was a complete performance on the line of scrimmage, and that's where it always starts."

Riley was feeling himself after the win, and rightfully so. USC was previously 4-11 against AP-ranked opponents under Riley and the program as a whole was 4-17 in its last 21 games against ranked teams. The Trojans had lost their last five games as a favorite against AP-ranked teams -- which began with a loss to Utah in the Pac-12 title game during Riley's first season with the program in 2022.

When USC hired Riley, the expectation was to win games like this to inject life into a program that was once the talk of the college football universe under coach Pete Carroll in the early 2000s. But the first four years of the Riley era at USC left much to be desired, with more postgame rants than marquee wins under his belt. In fact, Riley's tenure hit rock bottom last season with several late-game blunders -- including that loss to Michigan -- that derailed USC's hopes of a berth in the College Football Playoff by the first week of October.

Riley has had several notable chances at USC to make a statement by recording the "big win" that would push his program back in the right direction for good. However, the theme of his team shrinking in the game's biggest moments -- like last year against Michigan -- was all too familiar. Perhaps the most devastating result was when USC blew a 14-point second-half lead last season against Penn State, which caused his team to free-fall and nearly miss a bowl game.

That's why when Michigan scored a 69-yard touchdown to cut the deficit to 11 points midway through the fourth quarter, it might've been a déjà vu moment for anyone who has followed USC's program. Instead, USC marched down the field and threw the knock-out punch with a 29-yard touchdown run by Bryan Jackson to extend the lead to 18.

"It was a big opportunity we didn't want to miss," Riley said. "For those recruits and the people that were in the building tonight, I would imagine a lot of people would say that's what it used to feel like around here in the Coliseum. Epic atmosphere. The place was just on fire."

This game and this moment could be program-defining for Riley. After USC suffered a 34-32 loss to Illinois on a last-second field goal last month, this matchup against Michigan became essentially a "gotta-have-it" for the Trojans to get back into the CFP hunt with games against Notre Dame and Oregon looming on the schedule.

USC's dominant performance against Michigan was four years in the making for Riley. After falling short in so many big spots, Riley finally delivered a result that could change the narrative -- and USC's season -- while also vindicating why the program made the big investment to hire him in the first place.

"What a cool time," Riley said. "I think several years ago, it was kind of all what we dreamed up this would be."