BATON ROUGE, La. - With a second to spare, LSU kept it's national championship hopes alive and well. Matt Flynn threw a 22-yard touchdown pass to Demetrius Byrd with 1 second left to lift fifth-ranked LSU to a 30-24 victory over No. 18 Auburn on Saturday night.

Auburn defensive back Jerraud Powers, left, can't stop the winning touchdown catch by LSU receiver Demetrius Byrd, right, in the second half of their football game in Baton Rouge, La., Saturday, Oct. 20, 2007. LSU won, 30-24.(AP Photo/Alex Brandon)

A week after losing in triple overtime to Kentucky and giving up the No. 1 ranking, LSU couldn't afford a second straight loss.

Now with South Florida losing earlier in the week, LSU (7-1, 4-1 Southeastern Conference) is certain to move up to at least third in the BCS standings, behind only undefeated Ohio State, which also won, and possibly Boston College, which was idle this weekend.

The victory also puts LSU on the inside track to win the SEC West, as the winner of the Auburn-LSU rivalry has done in five of the past seven years.

Flynn finished with 319 yards passing and three touchdowns, the last on what seemed to be a risky play called by a coach who's shown he's not afraid to gamble.

Les Miles had converted five fourth downs in a dramatic 28-24 victory over Florida the last time LSU was at home. This time, he let Flynn take one last shot at the end zone with the clock winding down when the safer play would have been to set up for a potential game-winning field goal.

LSU had a timeout left, but the Tigers cut it awfully close on their final play.

Miles said those calls come from being confident in his players, who had come back from a 17-7 halftime deficit.

"They showed great character and great resolve and want — the way they played in the second half," Miles said.

Auburn's Brandon Cox, taking hits in the pocket but rolling out effectively when necessary, turned in a gutty performance, passing for 199 yards and a pair of touchdowns.

His last scoring pass, a 3-yard strike to Rodgeriqus Smith, gave Auburn a 24-23 lead with 3:21 to go.

It completed an 83-yard drive, which Auburn had the benefit of engineering without LSU standout defensive tackle Glenn Dorsey on the field. Dorsey left the game in the third quarter with an injured right leg after he was caught awkwardly in a pile at the line of scrimmage.

But Auburn (5-3, 3-2), following a game-long pattern of keeping the ball away from LSU returner Trindon Holliday, squibbed the kickoff, giving LSU the ball on its 42.

"We just weren't going to kick it to their returner," Auburn coach Tommy Tuberville said. "We still felt good about it. We didn't make the plays."

Flynn scrambled for 19 yards during the final drive, then took one more shot at the end zone instead of getting the ball in the middle of the field to set a field goal attempt. He floated a pass perfectly to the back of the end zone, where Byrd emerged from behind a defender and made a sliding catch, sending Tiger Stadium into a frenzy.

LSU extended its winning streak in Death Valley to 18 games. Auburn came in on a three-game winning streak that included impressive road wins over No. 14 Florida and Arkansas.

Jacob Hester gave LSU a 20-17 lead, diving for the pylon early in the fourth quarter after catching a swing-pass on third-and-goal from the 5. He also led a patient rushing attack that amassed 169 yards, all but 40 in the second half.

A flag was thrown on Hester's touchdown for LSU having not enough players line up on the line of scrimmage. But officials wanted to see a replay of the play to confirm that Hester had in fact got the pylon for a score. In doing so, they decided LSU was in fact lined up properly and picked up the flag.

Tuberville was furious and argued with officials for several minutes before the ensuing kickoff.

"That's obviously got to be looked at," Tuberville said. "There's a flag on the field. You've got to work that out before you start looking at (the replay). Unfortunately they did it the way you're not supposed to."

Auburn led 17-7 at halftime after getting touchdowns on Cox's 17-yard pass to Montez Billings and Carl Stewart's dive over the pile.

Flynn led LSU back with help from his best receiver, Early Doucet, back from a groin injury that had caused him to miss most of the last five games. Doucet made several clutch catches, finishing with seven receptions for 93 yards.

"The return with Early Doucet on the offensive side helped us a ton and we look forward to having him the rest of the way," Miles said.