LAS VEGAS — Ever been to a good Vegas show? The singing, dancing and theatrics. The smoke, lights and smells.

We saw one on Sunday night, not in some dingy casino ballroom or a dark hotel lobby, but in a football palace erected just off Las Vegas Boulevard. There was plenty of smoke (pregame fireworks caused a haze to linger for three quarters). There were lead characters and main actors (Heisman Trophy replacement quarterbacks Miller Moss and Garrett Nussmeier). There was even dancing (one LSU player was flagged for a hip-thrusting jig in the second quarter).

Singing, chanting and swaying? Had that too, a pair of boisterous fan bases, two of college football’s biggest brands colliding before them.

It had it all right down to a sensational closing act — a late-game drive, a heroic catch and gut-busting run for a winning touchdown.

USC and LSU delivered to millions watching a playoff-worthy performance, with a championship vibe, all unfolding on a holiday weekend Sunday evening — a thrilling, heart-pounding Vegas act that Wayne Newton himself would proudly endorse.

The score — USC 27, LSU 20 — doesn’t justify the beauty of it all, the intense moments, the stellar quarterback play, momentary defensive lapses and waves of side-splitting momentum swings.

And now we are left to dissect the show and review — or overreact — to a Week 1 game between two teams that, let’s be real, we don’t really know much about.

Can USC now seriously contend in its big bad new league?

Can LSU rebound to make a 12-team playoff?

What we saw on Sunday night was a Trojans defense, revamped and bolstered by a new coordinator, tackle better than any Lincoln Riley defense in his eight-year career as a head coach (the unit stuffed LSU on two critical fourth-quarter drives). We saw a quarterback, Miller Moss, who shined on the grandest stage after waiting three years for his shot (he completed 75% of his passes and finished with 378 yards).

We saw a receiver, Kyron Hudson, make two of the best catches you’ll ever see: a one-handed, acrobatic grab in the third quarter and a game-changing reception in the fourth, when he corralled a ball from Moss on USC’s final touchdown march despite a blow (a targeting blow, at that) from an LSU defender.

We saw, perhaps most surprising of all, a USC defense tackle, yes tackle. They stuffed the run (minus a 39-yard burst, LSU had just 78 yards rushing) and put together a first-quarter goal line stand (LSU failed on a fourth-and-goal from the 3).

Those superlatives made their coach the most pleased. Lincoln Riley seemed almost surprised by it all, certainly impressed, with a unit that a year ago ranked 119th nationally.

We did that? How? Are you sure?

Riley made one of the offseason’s most talked-about moves in firing coordinator Alex Grinch and hiring UCLA’s D’Anton Lynn, one of the most heralded young defensive minds in the game. A new coach. A new scheme. New players. A new mentality.

“I was proud of how hard and well we played and how much we trusted it and we didn’t panic. We kept grinding,” Riley said. There’s a “vibe” to the defense, he said — a confidence. “It was so cool to see that moment and in that arena, how much we trusted (the new system).”

The overreactions are obvious:

– Moss, sharp and crisp, composed and calm, is Riley’s latest Heisman Trophy contender.

– The USC defense, physical, aggressive and smart, is back to championship form.

– Riley, the $10 million dollar man in his third season, will finally deliver a championship to Los Angeles.

On the other side, the other $10 million man, Brian Kelly, was left “angry,” he told reporters afterward, mostly at an offense that failed to turn a one-score game into two in the second half. The Tigers had that chance twice, up 17-13 with ball possession and with momentum on their side.

They lost a yard on a third-and-1, stuffed by Lynn’s new-look defense. On another drive, they picked up three yards when they needed six, again stuffed by Lynn’s swift-tackling defenders short of the first-down line.

They wasted a 304-yard outing from new starter Nussmeier with old starter, Heisman winner Jayden Daniels, on the sideline watching. In the stands, those rowdy Louisianans flooded for the exits, into the dry heat of Vegas and, at some point, bound for a cross-country flight home, ticked off and (likely) hungover.

These are the games that make and break you. They get coaches fired and others hired, they enliven fan bases, inspire them and deprive them.

“That was a playoff game,” uttered USC athletic director Jen Cohen.

It certainly felt that way, two goliaths of the game from the two most powerful football leagues, each of their commissioners watching from this football palace, the bright lights of the Strip streaming in to illuminate just another magical Vegas show.

One with a new twist.

“Pretty good Big Ten football today,” Riley smiled.