Who were these players and what did they do to USC’s defense?

They were physical.

They made tackles in the open field.

They kept their team in the game when the attack stalled.

Finally, in Lincoln Riley’s third year as coach, the Trojans have a defense. Finally, under first-year defensive coordinator D’Anton Lynn, they have a defense that can strike fear into their opponents.

New quarterback Miller Moss threw for 378 yards and transfer running back Woody Marks scored two touchdowns, but the biggest revelations in their season-opener 27-20 win over No. 13 LSU came on the other side of the ball.

This defense has the Trojans dreaming again. This defense could make them relevant on the national stage in ways that their recent defenses couldn’t. This defense is the reason USC could be one of 12 teams to reach the College Football Playoff this season.

“This new defensive identity, I would say, is very different than in years past,” sophomore defensive end Braylan Shelby said.

There were countless magicians performing on the nearby Las Vegas Strip on Sunday night, but none more special than Lynn, who had previously transformed UCLA’s defense into the nation’s best against the run.

“We had some pretty good Big Ten football today,” Riley said.

LSU drove the ball to USC’s 3-yard line on the game’s opening drive, but was held out of the end zone when linebacker Mason Cobb executed a fourth-down blitz, forcing Tigers quarterback Garrett Nussmeier to throw an errant pass.

Cobb also secured the win by intercepting a pass from Nussmeier with four seconds left on the clock.

The Trojans gave up an average of 186.5 yards per game on the ground last season. On Sunday, against an LSU team with a physical offensive line, they allowed just 117 yards, 39 of which came on one play.

Shelby said, “We knew what they thought our weaknesses would be.”

USC defensive end Sam Greene celebrates with his family in the stands after the Trojans’ victory on Sunday.

(Robert Gauthier / Los Angeles Times)

In principle, USC would be just as soft as it was under Lynn’s predecessor, Alex Grinch.

In pre-game interviews, LSU forward Will Campbell compared the matchup with USC to a “fistfight” and was candid about how the Tigers expected to win.

“We’re going to run the ball,” Campbell said.

Lynn made sure that wouldn’t happen.

“We had to turn that around when it came to this season,” Shelby said. “This whole offseason we went with the mindset of, ‘We’ve got to turn this around, we can’t be known like this.’ This whole offseason has been about stopping the run. In previous seasons that’s been a big thing for us, so turning that around has been a big thing for us this year and I feel like we’re doing that so far.”

Part of the reason the Trojans looked like they had a new defense was because they actually had a new defense. They started with six transfers on defense, including tackles Gavin Meyer and Nate Clifton.

Meyer is 6 feet 3 inches tall and weighs 295 pounds, and Clifton is 6 feet 3 inches tall and weighs 300 pounds.

USC defensive end Lorenzo Cowan (37) creates a confetti angel on the field after the Trojans’ win on Sunday.

(Robert Gauthier / Los Angeles Times)

“There were times in the game where you could definitely see how great our defense was, how much stronger we were at the point of contact,” Shelby said.

The defense was especially dominant in the most critical part of the game, after LSU took a 17-13 lead late in the third quarter on a 13-yard reception by Aaron Anderson. The Tigers had a chance to break the game open. The Trojans didn’t let it happen, forcing them to punt on consecutive possessions.

The defense allowed USC to regain the lead to 20-17 when Moss completed a 28-yard pass to receiver Ja’Kobi Lane.

“We fought the whole game,” Riley said.

Now that the long-standing issue has apparently been resolved, Riley, who still had issues with game management, could be the biggest question mark for USC.

He wasted precious seconds early in his team’s final drive of the first half, forcing him to decide whether to take a shot at the end zone or settle for a field goal attempt that kicker Michael Lantz missed. He wasted two timeouts early in the fourth quarter.

Riley also seems to be a bit uncomfortable in the spotlight. He has repeatedly stated that he doesn’t care what is written or said about him in the media. This is usually a sign that someone cares a lot about what is written or said about him.

But that’s a problem for another day. For now, the Trojans can celebrate. They have a defense. They have a chance.