The Tiger Stadium crowd was in a frenzy and LSU was 6 yards from a go-ahead touchdown after Kendell Beckwith pounced on T.J. Yeldon's fumble with little more than a minute to go.
On the next play, LSU started going backward — a bad omen when the opponent is Alabama and the venue is Death Valley, where the Crimson Tide has found dramatic ways to win plenty of times before.
A 15-yard unsportsmanlike conduct penalty on guard Vadal Alexander led No. 14 LSU to settle for Colby Delahoussaye's go-ahead field goal with 50 seconds left, which was enough time for fourth-ranked Alabama and quarterback Blake Sims to tie the game in the final seconds before pulling out a 20-13 victory in overtime Saturday night.
"The penalty changed the complexion of the game," LSU coach Les Miles said, adding that he was going to "investigate" the call when he reviews video of the game. "We don't get a 15-yard penalty down there ... we are talking about driving in for a 7-pointer."
If the Tigers (7-3, 3-3 Southeastern Conference) had been able to hold on, they would have pulled into a four-way tie for second place in the SEC West with Alabama, Auburn and Mississippi.
Instead, Alabama (8-1, 5-1, No. 5 CFP) moved into second place alone in the SEC West with a game against first-place and top-ranked Mississippi State still left on its schedule.
After the Tigers took their late lead, there were several public address announcements urging fans not to run on the field following the game, as they'd done after an upset of Ole Miss.
Those announcements turned out to be premature.
LSU's defense, which dominated much of night to the delight of a sellout crowd of 102,321, was unable to make one last stand after kickoff specialist Trent Domingue yanked his kick out of bounds, giving Alabama the ball on its 35 with 50 seconds to go.
Sims scrambled for one first down, then hit several clutch passes, none bigger than a 22-yarder to Christion Jones, who made a sprawling catch on the LSU 26. Sims then hit DeAndrew White along the sideline at the 10 to set up the tying kick, a 27-yarder by Adam Griffith — who missed from the same distance, and same right-to-left angle, in the first half.
"I've got a team that played a great game and played a tough game," Miles said. "That is a tough one. I've got a bad taste in my mouth about that game."
In overtime, Sims hit White for a 6-yard touchdown pass. LSU had to score a touchdown to keep the game going, but couldn't even manage a first down.
Alabama's comeback was reminiscent of its 2012 victory in Tiger Stadium, decided by a drive that ended with Yeldon taking A.J. McCarron's screen pass 28 yards for a winning touchdown in the final minute. Alabama is 26-9-2 in Tiger Stadium, with victories in three of its past four visits.
"I was happy that I had the opportunity to be in that situation," Sims said. "I watched film on A.J. I saw the composure that he had and I was just glad I was able to do the same thing."
LSU quarterback Anthony Jennings completed eight of 26 passes for 76 yards, but one was a 14-yard TD to Malachi Dupre.
"This one stings," Dupre said. "It is our seniors' last game in Tiger Stadium. It didn't go the way we wanted it to go. We fought hard all game and these are the tough ones, the ones you lose at the last second. We are going to learn from it."
Leonard Fournette rushed for 79 yards for the Tigers, who gained 183 yards on the ground against a defense that came in allowing only 78 yards rushing per game.
LSU scored first on one of only two passes Jennings completed in the first half — a fade to Dupre along the left side of the end zone.
Alabama was moving the ball, but saw a 17-play drive go for naught when Griffith's field goal try from the right hash smacked off the left upright in the second quarter. Alabama broke through on its next series when Sims hit Amari Cooper over the middle for his tackle-breaking score.
Eddie Jackson's interception of Jennings' pass intended for Travin Dural, who slipped on his route, led to Griffith's 39-yard field goal to make it 10-7 at halftime.
LSU tied it at 10 on Delahoussaye's 35-yard field goal in the third quarter.