LSU had the misfortune of playing in the same conference as top-ranked Auburn, which won the SEC and earned the league's automatic berth to a BCS bowl.
Texas A&M finished in a first-place tie in the Big 12 South, but its BCS fate was decided by a computer.
These programs renew their rivalry in the 75th edition of the Cotton Bowl at Cowboys Stadium on Friday night.
The 11th-ranked Tigers went 10-2 overall and 6-2 in the SEC West, but are in the same division as Auburn, which went 13-0 -- 8-0 in conference play -- to set up a meeting with Oregon for the national title.
LSU's only losses came at then-No. 5 Auburn and at then-No. 12 Arkansas. The 31-23 defeat to the Razorbacks in the regular-season finale Nov. 27 ended any chance for a BCS bowl appearance.
"We are very excited about going to Dallas for the AT&T Cotton Bowl Classic," director of athletics and vice chancellor Joe Alleva told LSU's official website. "Once it looked like we were out of the running for a BCS bowl game, we turned our attention to Dallas and getting into the Cotton Bowl.
"This is the bowl that our players and coaches wanted to play in."
LSU's last appearance in the Cotton Bowl came Jan. 1, 2003 -- a 35-20 loss to Texas -- following a 37-year absence. The Tigers are 2-1-1 in the event.
After the 2003 season, current LSU coach Les Miles took Oklahoma State to the Cotton Bowl and lost 31-28 to Mississippi.
"The Cotton Bowl is one of the all-time great college bowl games and to be able to participate in what is the 75th anniversary of this legendary game will be special for our team," Miles said. "I've been here before as a head coach so I know firsthand what a first-class bowl this is.
"The atmosphere is no different than if you were playing in the national championship game. ... Texas A&M has an outstanding program and we are looking forward to renewing our long-standing rivalry with them."
The Tigers will face No. 18 Texas A&M (9-3) for the first time since 1995. The rivalry dates to 1899, and the Aggies have won the last five matchups but trail 26-20-3 in the series. They last met in a bowl in the 1944 Orange, won 19-14 by LSU.
"Any time you play a team outside your conference, especially a team the caliber of Texas A&M, gets you fired up," running back Stevan Ridley said. "They come from a competitive conference in the Big 12 and I'm sure they will pack the place with their fans nearby."
The Aggies finished 6-2 against that competition in the Big 12, tying Oklahoma and Oklahoma State for the top spot in the South. The Sooners, though, got into the conference title game with the help of a BCS standings tiebreaker.
Texas A&M defeated Oklahoma 33-19 and beat the other participant in the Big 12 title game, Nebraska, 9-6. The Aggies ended the regular season on a six-game winning streak.
"We have played one of the toughest schedules in the country and it is appropriate we will face a great challenge from a quality LSU program," director of athletics Bill Byrne said. "It should make for one of the best matchups in the bowl season."
Texas A&M's late-season surge came after coach Mike Sherman benched starting quarterback Jerrod Johnson for Ryan Tannehill following a 3-3 start.
Tannehill, who had been one of the Aggies' best receivers while doubling as the backup QB, completed 65.1 percent of his passes for 1,409 yards with 11 touchdowns and three interceptions over the final six games.
A change in the backfield also helped, as Cyrus Gray took over for starting tailback Christine Michael after he broke his leg in October.
Gray finished with six consecutive 100-yard games and ran for 223 in a 24-17 win over Texas in the regular-season finale Nov. 25.
Von Miller had a key interception in the final minutes of that game, and the Texas A&M senior won the Butkus Award as college football's best linebacker. He led the Big 12 in sacks for the second straight season with 9 1/2.
Miller and the Aggies will be trying to stop an LSU offense that has struggled. The Tigers are 107th in the FBS with 155.4 passing yards per game and 92nd in total offense with an average of 332.6.
They are led on the ground by Ridley, who rushed for 1,042 yards and 14 touchdowns. Jordan Jefferson and Jarrett Lee split time at quarterback, and they combined for 1,826 yards with six TDs and 10 INTs.
LSU's defense, however, has been stellar. The Tigers are eighth in total defense (301.7), tied for ninth in scoring defense (17.8) and 10th against the pass (165.8).
Cornerback Patrick Peterson won the Jim Thorpe Award as the nation's best defensive back and the Chuck Bednarik Award as the top defensive player.
"We get to renew a rivalry with a great Texas A&M team. I watched them against Texas and they are a great team with a traditional offense but can still run spread and I-formation," Peterson said.
LSU, 21-19-1 in bowl games, is making its school-record 11th straight postseason appearance. The Aggies are making their 12th trip to the Cotton Bowl (4-7) and are 13-18 in bowl appearances, losing four straight and eight of nine.
AccuScore has powered more than 10,000 simulations for every College Football game on ESPN.com, calculating how each team's performance changes in response to game conditions and opponent's abilities. Each game is simulated and the game is replayed a minimum of 10,000 times to generate forecasted winning percentages.
Texas A&M flirted with the SEC over the summer, but the Aggies will get a chance to beat an SEC team for the first time since 1995 when they face LSU. Texas A&M is 0-3 in the past two seasons against the conference, but the Tigers' defense will make life hard on the Aggies' offense. There's a silver lining for Texas A&M, though. Les Miles will be without his mojo: This game is on artificial turf. -- David Ubben