LSU couldn’t finish what would have been one of the most significant victories in Tiger Stadium history Saturday night just as it couldn’t finish what would have been the most significant season in school history 10 months earlier.

The Tigers were on the verge of avenging a 21-0 loss to Alabama in the BCS Championship game in January, but AJ McCarron drove the Crimson Tide 72 yards and threw a 28-yard touchdown pass with 51 seconds left to give the defending national champion a 21-17 victory in front of a Tiger Stadium-record crowd of 93,374.

“We let this get away,” LSU defensive end Sam Montgomery said. “We had tons of opportunities to maximize in the game. But we couldn’t put them away. Sometimes, it’s not the best team, but it’s the most disciplined team. It’s tough. It was slow death.”

McCarron’s heroics, which culminated in a a scoring pass to T.J. Yeldon, came after LSU had turned the game 180 degrees after halftime. Alabama led 14-3 at halftime, but the Tigers held the Tide to one second-half first down until the final drive and Zach Mettenberger guided LSU to two second-half touchdowns.

Top-ranked Alabama (9-0, 6-0 in the Southeastern Conference) remained in the driver’s seat to win the West Division. The Tide can clinch the West outright with a victory at home against Texas A&M next week.

No. 5 LSU, which hosts to Mississippi State on Saturday, saw its school-record 22-game home winning streak end.

The Tigers’ shaky passing game came to life as Mettenberger led an assault on the nation’s No. 1 defense, throwing for a season-high 293 yards. Jarvis Landry (eight catches, 76 yards, one touchdown) and Odell Beckham Jr. (four catches, 73 yards) made big plays.

“The receivers and the rest of the offense have known what we were fully capable of all year,” Mettenberger said. “We were finally clicking tonight. But as well as I played, I would trade 150 yards and three interceptions if we had won. It hurts; it definitely hurts.

“We had a great rhythm. We played with confidence, executed well and didn’t make a lot of mistakes.”

Freshman Jeremy Hill ran like a senior, gaining 107 yards and scoring a touchdown that started the second-half surge.

LSU was in position to put the game away as it held a 17-14 and the football in the waning minutes of the second half. The Tigers had a first down at the Tide 32. J.C. Copeland gained 3 yards, and Hill lost 3 and gained 4. The runs forced Bama to use its last two timeouts, but Drew Alleman was wide left on a 45-yard field goal with 1:34 left.

“We thought we could get an easy field goal and didn’t want an interception,” Mettenberger said. “I don’t blame (the play calls). Nobody can blame Drew. We left a lot of offense on the table and had a lot of drives we didn’t finish.”

That gave McCarron the ball at the 28 with 1:34 left. McCarron hit three quick completions to Kevin Norwood for gains of 18, 15 and 11 yards to the Tigers 28. After an incompletion to Norwood in the end zone, the Tide called a screen against an LSU blitz and McCarron lofted the ball to Yeldon, who just had to cut back on safety Craig Loston to sprint into the end zone with 51 seconds left.

“We told our players that they would have to overcome a lot of adversity to win a game here,” Bama coach Nick Saban said. “When things went bad and the momentum of the game changed, that’s what we kept talking to them about. They kept their poise, they kept playing and they kept competing.”

LSU coach Les Miles said there was a missed assignment on the touchdown.

“We held them for the better part of the game, but it just goes to show you it takes only one error to cost you the game,” safety Eric Reid said. “It’s just so unfortunate that it happened to us tonight. One mistake cost us the game.”

LSU trailed 14-3 and was sputtering on offense before Hill’s 1-yard touchdown run completed a 58-yard drive late in the third quarter.

The Tigers tried to capitalize on the momentum by trying an onside kick. Kicker James Hairston fell on the ball for the Tigers, but the officials ruled that he touched the ball before it went the requisite 10 yards and the ruling was upheld on review.

LSU had tried another trick play earlier as a fake field goal failed when holder Brad Wing’s pass to Alleman in fourth-and-12 pass lost 2 yards. Later Miles had Alleman try a 54-yard field goal, which would have been a career long, but the kick was short.

“I wish I could have had a couple of my calls back,” Miles said.

Bama quickly marched toward the goal line, but on third-and-3 from the 10, T.J. Yeldon dropped a handoff from McCarron and Montgomery recovered for LSU.

The Tigers drove 90 yards and Mettenberger threw a 14-yard touchdown pass to Landry to give LSU a 17-14 lead with 12:58 left in the game.

After a Tide punt, the Tigers marched to the Bama 24, but on fourth-and-1, but running back Spencer Ware was stopped for no gain after lining up under center.

The biggest question coming into the game was whether LSU could avoid the offensive futility it had in the BCS title game. The Tigers showed right away that things wouldn’t be that bad, but Bama showed they wouldn’t be easy either.

LSU received the opening kickoff and needed just six plays to cross midfield, something it didn’t accomplished until midway through the fourth quarter in January.

The drive stalled at the Tide 46 after Mettenberger threw two incompletions, but the Tigers got the ball back after a three-and-out.

This time it took just four plays for LSU to cross midfield again. The Tigers reached the 21, but stalled after two moiré Mettenberger incompletions. Alleman’s 38-yard field goal provided a 3-0 lead for LSU, whose only lead in the two meetingslast season came on Alleman’s field goal on the last play of overtime in Tuscaloosa.

Bama, which faced only one deficit — for 14 seconds against Ole Miss — drove to the LSU 39 on the ensuing possession, but pass interference penalty on Kevin Norwood short-circuited the drive.

But the deficit didn’t last long as the Tide forced a punt on the Tigers’ next possession, and McCarron found a rhythm. He directed the longest drive against LSU this season as Bama went 92 yards and took a 7-3 lead when Eddie Lacy ran 7 yards for a touchdown.

McCarron’s 9-yard touchdown run just before the half gave the Tide a 14-3 lead.