LAS VEGAS — The outcome felt inevitable as Southern Cal entered LSU territory. A pass over the middle. A slant pass to midfield. A deep completion down the sideline, then free yards from another penalty. The clock was ticking toward overtime, if only LSU could send it there, but the end was all but a foregone conclusion.

USC running back Woody Marks scored a touchdown with eight seconds left on the clock Sunday night at Allegiant Stadium and No. 13 LSU fell 27-20 to the No. 23 Trojans as the offense faltered and had multiple chances to take control in the second half.

“I think this is the first time since I’ve been here that I’ve really been mad at our football team,” LSU coach Brian Kelly said.

It was a crushing loss for LSU, which has lost five straight season openers for the first time since 1991-95. The team hasn’t won one since 2019 and has yet to win its first game in three years under Kelly.

“Obviously, when we get up in a game, we don’t know how to conduct ourselves,” Kelly said. “You have to have a killer instinct in this game. You have to put teams away. We had a chance to put this team away, and we get complacent. We make more mistakes when we’re ahead instead of having a better focus and a steely-eyed killer instinct. It’s disappointing.”

LSU took its first lead, trailing 13-10 in the third quarter. Sixth-year running back John Emery fueled the drive with 49 yards rushing in his first game since tearing his anterior cruciate ligament last fall. Then Garrett Nussmeier threw a 13-yard touchdown to redshirt sophomore wide receiver Aaron Anderson.

The score stayed there as LSU’s defense forced a punt and a turnover on downs. When USC went ahead on fourth-and-9 from LSU’s 37-yard line early in the fourth quarter, defensive end Sai’vion Jones was able to block a pass at the line of scrimmage.

But after the play, senior safety Major Burns was assessed an unsportsmanlike conduct penalty. Senior receiver Kyren Lacy was also assessed unsportsmanlike conduct during a touchdown celebration in the first half. LSU was assessed 10 plays for 99 yards, while USC was flagged six times for 50 yards.

“What concerns me the most is the personal fouls,” Kelly said. “The selfish penalties. Both of those led to scores. They’re undisciplined penalties and those fall on me. We pride ourselves on having a disciplined program, but we clearly didn’t do a good enough job because it affected the game.”

After the turnover on downs, LSU went three and out for just the second time all game. USC quarterback Miller Moss then led a three-play, 64-yard drive to retake the lead. He capitalized on an offsides penalty and threw a 28-yard touchdown to wide receiver Ja’Kobi Lane with sophomore corner Ashton Stamps in coverage.

Down 20-17, Nussmeier found Anderson for a 41-yard gain on third down. But once the Tigers reached the red zone, they gained 2 yards on three plays. LSU settled for a 31-yard field goal.

“We had chances to step on their throats,” Nussmeier said. “We had a chance to decide the game. We didn’t.”

With 1:47 left, USC got into LSU territory when Moss picked through the secondary. He completed 27 of 36 passes for 378 yards and one touchdown. The final straw was a 20-yard completion down the left sideline. LSU safety Jardin Gilbert was penalized for targeting the tackle, sending USC into the red zone.

Marks scored on the next play, after which Nussmeier threw an interception, deciding another loss in the season opener.

“We left a lot of points there,” Kelly said. “We were up and down the field, but when you’re not scoring points when you’re in the red zone, like we weren’t tonight, you lose a game by one possession.”

Kelly said he was upset with LSU’s inability to play complementary football, the two unsportsmanlike penalties and the way the players conducted themselves when they had a chance to take over the game in the second half.

The Tigers finished 5 of 13 on third down and had three drives deep into USC territory that resulted in six points. After LSU took the lead in the third quarter, the next four possessions resulted in two punts, a field goal and an interception.

The bulk of USC’s offensive production came through the air, as it navigated a secondary full of questions entering the season. While the defense showed signs of improvement, limiting USC to 69 yards rushing and 3 of 9 on third down, Moss averaged 10.5 yards per attempt.

“We put way too much pressure on our defense, and they’re not ready for it yet,” Kelly said.

For the third year in a row, LSU must find a way to make amends after a brutal loss in the season opener. It has happened before, but the margin for error has narrowed.

During his post-match press conference, Kelly slammed his fist on the table and raised his voice in anger.

“We’re sitting here AGAIN talking about the same things,” Kelly said. “About not finishing when you have an opponent in a position to put them away. But what we’re doing on the sideline is feeling like the game is over, and I’m so angry about it that I have to do something about it.

“I’m not doing a good enough job as a coach and I have to coach them better because it’s unacceptable that we didn’t find a way to win this football match.”