Down 22 points at halftime, Southeastern Conference cellar-dweller Missouri threatened to spoil Senior Night for LSU on a festive evening in the Pete Maravich Assembly Center.

But in a roller coaster of a season in which it has become accustomed to watching substantial leads slip away in the second half, the LSU basketball team managed to hang on for an 80-71 victory over Missouri.

With only one senior being able to take the court because an injured Keith Hornsby missed his third consecutive game, LSU’s youth was served when things got extremely tense.

Four first-year players combined for 58 of the 80 points as LSU remained one game out of first place in the SEC standings going into the regular-season finale Saturday at Kentucky.

Kentucky is tied for the lead with Texas A&M after both teams won Tuesday night. LSU and Vanderbilt remained in a tie for third, a half-game ahead of South Carolina. which plays Georgia on Thursday night.

LSU (18-12, 11-6) could be playing for a share of the league’s regular-season title against Kentucky pending the outcome of Vanderbilt’s game at Texas A&M, which tips off two hours before the LSU-Kentucky contest.

But before they could set that up, LSU had to hold off Missouri after a solid first half.

“We got off to a tremendous start. … The first 20 minutes were some of the best we’ve played all year,” LSU coach Johnny Jones said of his team, which shot 58.1 percent from the field in that half. “We had 12 or 13 assists at the half, we were getting in the passing lanes, helping on the post guys. You have to commend Missouri for making plays in the second half, and we did not do a great job on the offensive end.”

Freshman Ben Simmons scored a game-high 22 points for LSU, while fellow freshman Antonio Blakeney finished with 18 points.

Simmons also grabbed 14 rebounds for his conference-leading 21st double-double of the season and came within three assists of a triple-double.

Sophomore transfer Craig Victor and freshman Brandon Sampson continued the first-year trend for LSU.

Victor added 10 points, and Sampson came off the bench for eight first-half points as LSU rolled to a commanding 46-24 halftime advantage. LSU also got 11 points from junior Tim Quarterman.

But Missouri (10-20, 3-14) roared back in the second half and outscored LSU 47-34 on the strength of six 3-point baskets, getting the deficit under double digits with 7:46 to play on a basket by forward Ryan Rosburg.

It was the first time Missouri had gotten within 10 points of LSU since the 9:47 mark of the first half when Sampson scored on a pass from Simmons to stake their team to a 21-10 lead.

From there, LSU went on a 25-14 run to end the first half and take a healthy lead to the locker room.

But just like in Saturday night’s nail-biting 96-91 win against Florida, when LSU led by as many as 18 points in the second half, the PMAC crowd couldn’t breathe easy.

Missouri came out and scored the first six points of the second half to set the tone for a possible comeback and shortly thereafter buried three 3-point shots — two by Kevin Puryear and one by Namon Wright — to quickly trim LSU’s lead to 15 points.

“When teams do get big leads, they have the ability to lose focus and not be as sharp,” Jones said. “I think we were a victim of that. That’s an area where we have to continue to grow.”

Sparked by that quick outburst coming out of the locker room, Missouri went on to make 18-of-30 field-goal attempts in the second half for 60.0 percent after hitting only 35.7 percent in the first 20 minutes.

“Teams are not going to give up.,” Jones said “You have to commend Missouri’s basketball team. They came out the second half and played extremely well.”

Missouri kept chipping away and got as close as three points at 65-62 with 4:48 remaining on a 3-point shot by K.J. Walton before Blakeney and Quarterman sandwiched 3-pointers of their own around a basket by Terrence Phillips.

At that point, Simmons, who was 10-of-11 from the free-throw line, made six in a row down the stretch, and Blakeney connected for another field goal with 3:03 left to help LSU maintain a five- to nine-point lead the rest of the way.

Rosburg scored 13 points, one of three players with that total for Missouri, before fouling out with 1:57 to play in the game.

Phillips and Puryear matched Rosburg’s total with 13 each. Walton, who was 3-of-3 from beyond the 3-point arc in the second half, scored all 11 of his points after halftime but couldn’t overcome LSU’s big lead early.

“I was pleased that we were able to finish the right way,” Jones said. “We were 8-1 in conference play at home. That’s something to be excited about.”