ATLANTA — LSU’s undefeated 2011 season ended with the hollow thud of a lopsided 21-0 loss to Alabama in the BCS National Championship Game in which the Tigers seemed powerless to change the outcome.

LSU’s 2012 season ended Monday night with the bitter pain of a 25-24 loss to Clemson in the Chick-fil-A Bowl, in which the Tigers had multiple opportunities to pull out the victory but couldn’t convert any of them.

Despite being outgained the entire night, No. 9 LSU took a 24-13 lead into the fourth quarter and appeared to be on its way to its sixth season of 11 wins or more under eighth-year coach Les Miles.

But LSU (10-3) managed just 1 net yard on six offensive plays in the final quarter as No. 14 Clemson (169 fourth-quarter yards) stormed back to win.

Chandler Catanzaro’s 37-yard field goal as time expired gave Clemson (11-2) its only lead of this dramatic showdown, but it was the only lead that counted.

“I was very confident,” said Catanzaro, who missed one field goal all season but had a second-quarter extra-point attempt blocked by defensive tackle Bennie Logan. “I have kicked a game-winner before. I just went out there and kicked it.”

It was the first time LSU has felt the gut kick of defeat in six appearances in the Chick-fil-A (formerly Peach) Bowl. It is also the first time LSU has lost back-to-back bowl games since the Tigers lost four straight following the 1982, 1984, 1985 and 1986 seasons.

“We have a very quality football team,” Miles said. “The guys have spent every (bit of) energy they had tonight. This moment, this is a painful one.”

At first, the pain was all Clemson’s.

Starting wide receiver Sammy Watkins fumbled on the game’s second play and did not return with a leg injury. LSU strong safety Craig Loston recovered at the 23, and two plays later, his team had a 7-0 lead, as Jeremy Hill scored on a 17-yard run.

Hill broke free on a 57-yard touchdown run on the first play from scrimmage to start the second half put LSU up 21-13. The former Redemptorist tailback finished with 124 yards on just 12 carries, his 12 touchdowns this season setting an LSU freshman record.

Another Clemson fumble by Andre Ellington was recovered by free safety Eric Reid at the CU 29 with 7:34 left in the third.

LSU had perhaps a killer touchdown in its grasp, but wide receiver Jarvis Landry was unable to hold on to a pass in the end zone by Zach Mettenberger. LSU had to settle for a 20-yard Drew Alleman field goal and a 24-13 lead with 4:49 left in the third.

Clemson pulled within 24-22 on a Catanzaro field goal and a 12-yard TD pass from Tajh Boyd to DeAndre Hopkins with 2:47 left. LSU took over at its 39 after a popup kickoff, then began a brief series that will spark months of second-guessing.

With Clemson stacking the line to stop the run, Mettenberger found wideout Kadron Boone for 8 yards on the left sideline.

Instead of trying to gain 2 yards on two downs and at least force Clemson to start burning its three timeouts, Mettenberger overthrew Landry in the right flat when he was open for a first down. A third-down pass was batted down by defensive end Malliciah Goodman, who had three of Clemson’s six sacks on Mettenberger.

Clemson took over at its 20 with 1:39 left after a 53-yard punt by Jamie Keehn bounced into the end zone. Greenwood, S.C., native Sam Montgomery sacked Boyd for a 6-yard loss to force a fourth-and-16 at the CU 14, but Boyd then found Hopkins for the play of the game, a 26-yard reception to the 40.

Five more plays moved the ball to the LSU 20, from where Catanzaro made his game-winner, the last of Clemson’s 100 offensive plays. Clemson finished with 445 total yards.

“I don’t think I’ve ever gone so hard in my life,” Montgomery said. “To zone out and play through that with so much emotion is something I’ve never experienced in my life.”

LSU managed just 219 yards and nine first downs on 48 plays.

While Mettenberger returns to lead a potentially improved offense in 2013, the LSU defense faces an uncertain future.

Six juniors are considering whether to make themselves available for April’s NFL draft: middle linebacker Kevin Minter (19 tackles Monday), ends Barkevious Mingo and Montgomery, Logan, Reid and cornerback Tharold Simon.

Tailbacks Spencer Ware and Michael Ford are also considering leaving early.

Punter Brad Wing, suspended for the bowl game for violating unspecified team rules, tweeted Monday that he would announce his draft plans Tuesday. When Tuesday came, Wing posted a Twitter message saying he would announce Wednesday.

Wing is a draft-eligible third-year sophomore.

“These guys are making a lifetime decision,” Mettenberger said. “If it’s best for them and their families to leave, then that’s just part of the game — but of course I’ll be politicking for them to stay.”

LSU is now 9-2 in the Georgia Dome and 5-3 in postseason games under Miles, but has lost three of its last four. This was only LSU’s second loss in 38 nonconference games under Miles, the other being the Tigers’ 19-17 loss to Penn State in the 2010 Capital One Bowl.

Despite the defeat, Mettenberger still struck a defiant chord.

“As far as I’m concerned, we’re three minutes from being 13-0 right now,” he said, referring to LSU’s three losses to Florida, Alabama and Clemson by a combined 13 points. “It’s tough, but it just shows us that we have to work harder and get the lucky bounces that we need.”

Still, Mettenberger admitted: “This will probably eat at me until we strap up and play TCU to start next year.”

LSU will open its next season against the Horned Frogs where the Tigers really wanted to be once the BCS door was closed on them: at Cowboys Stadium, home of the Cotton Bowl, Aug. 31 in the Cowboys Classic.

With an offseason of discontent facing LSU once again, it’s an opener that can’t come soon enough.