HATTIESBURG, Miss. —  The little things cost LSU a big-time opportunity Monday afternoon.

Fundamentals, as they say in baseball and the stock exchange.

LSU shorted the market on them in the NCAA regional final here — pitching, catching, those sort of things — sending the Tigers home to turn in their equipment instead of hosting an NCAA super regional.

Regional host Southern Miss had a much better handle on basic baseball in a back-and-forth game before pushing across a run in the top of the ninth for an 8-7 victory.

Southern Miss’ game-winning ninth inning was text book — back to back singles to put runners on the corners, followed by Danny Lynch’s go-ahead sacrifice fly.

But that’s not where LSU (40-22) lost the game that ended its season.

And the Tigers kept fighting back, no question.

But, much to the merriment of a raucous crowd cheering on the Eagles and out-shouting a good showing from purple and gold fans, the usual LSU mischief and hijinks in the field and on the mound cost them a chance to host a super regional for the first time since 2019.

“I wanted to take this team to Omaha so bad,” Johnson said “It hurts because it I wanted to do it with this team. I knew how special it would be.”

Instead, Southern Miss (47-17) will host its first super regional in school history in what should be a rollicking weekend with upstate rival Ole Miss coming to town after winning the Miami regional.

“We beat a very good program just now in LSU,” USM coach Scott Berry said. “I’m a big fan of LSU and Jay Johnson, the way he does things.”

LSU, which had mega-comebacks to start the tournament 2-0,  gave it their best shot — had a chance to win almost in spite of itself.

After falling behind 7-4 in the top of the seventh, LSU got two back on back-to-back RBI singles by Tre’ Morgan and Jordan Thompson in the bottom of the inning and tied it at 7-all when Gavin Dugas led off the eighth with a solo home run.

“That’s what we did all this tournament — show fight,” Johnson said. “I’m proud of our team for that.”

The comeback wouldn’t hold.

“It’s a simple game, honestly,” Johnson said. “They’re infinitely better on the mound than than we are.”

And, he might have added, in the field.

The Eagles 4-run seventh inning and a 2-run third inning had LSU’s slippery fingerprints all over them after fashioning leads of 4-1 and 4-3 in the early going.

Southern Miss tied the game in that seventh before even managing a hit in the inning, then went ahead on the first single of the inning.

Typically silly LSU stuff, even though the Tigers were officially charged with only one (very costly) error.

Reliever Jacob Hasty walked the leadoff man in the seventh, luring out Devin “Jeckyl-and-Hyde” Fontenot, the unlikely pitching star of Friday’s comeback against Kennesaw State.

That was Good Devin — last year it survived a rocky ninth inning to seal LSU’s regional-clinching victory at Eugene, Oregon.

But LSU probably milked that gag too far, getting the other side — the heartburn side — of the senior right-hander this time.

He hit the first batter he faced — his seventh unintended target of the season — and promptly complicated the crisis when he followed it with a fumbled sacrifice bunt to load the bases, the Tigers only charged error.

Regional MVP Christopher Sargent’s sacrifice fly tied it and Slade Wilks singled off the third Tiger pitcher of the inning, Bryce Collins, for a 5-4 USM lead.

It got worse for the fourth reliever of the inning as Trent Vietmier gave up a 2-run single for a 7-4 USM lead that could have already been over.

For those keeping score at home: Four runs on just two hits — a 4-3 LSU lead morphing into a 7-4 deficit.

All told, LSU went to the bullpen six times — and none of the first five relievers retired the first batter they faced.

“I think we’ve got to pitch better,” Johnson said.

Closer Paul Gervace, first out of the bullpen for starter Ma’Khail Hilliard in the third inning, didn’t have his sharpest stuff, but was resilient after giving two runs in the fourth, not all of his own doing, that got USM to within a run. He wiggled out of a one-out, second-and-third situation in the fifth and a leadoff double in the sixth.

But USM’s 2-run fourth inning summed up the little things that have hindered LSU most of the season.

The only hit to the outfield was the third-out fly ball and officially there were no Tigers’ errors. But the Eagles got the pair of runs on two infield “singles” — plays that could have been made — a walk and an inning-changing passed ball.

It began with Sargent’s single off shortstop Jordan Thompson’s glove. Gervace then walked a batter and Danny Lynch hit one off Gervace’s glove that loaded the bases.

The first run scored on a passed ball by catcher Tyler McManus, which also moved runners to second and third.

Thus, after Gervace fanned Will McGillis for the first out, what would have been tailor-made double-play ground ball by Gabe Montenegro could only get one as the second run scored.

The little things again. They’re the reason the Tigers won’t have a big home party this weekend.

“I’m at a loss for words right now,” LSU star Dylan Crews said. “But it sucks.”