TUSCALOOSA, Ala. -- Johnny Football and the SEC newbies from Texas A&M took down the biggest bully in their new neighborhood and left No. 1 Alabama with badly bruised national championship hopes.

Johnny Manziel, better known around Texas as Johnny Football, staked the 15th-ranked Aggies to a three-touchdown lead in the first quarter, and Texas A&M held on to beat the Crimson Tide 29-24 on Saturday.

The Aggies (8-2, 5-2), playing in the Southeastern Conference for the first season after ditching the Big 12, also might have ended the league's run of BCS titles at six years.

The defending national champion Crimson Tide (9-1, 6-1), who have been No. 1 almost all season and had won 13 straight, didn't go quietly.

AJ McCarron nearly pulled off a second straight scintillating comeback. He threw one touchdown pass and motored the ball downfield before Deshazor Everett stepped in front of his fourth-down pass at the goal line with 1:36 left.

Manziel passed for 253 yards and rushed for 92, confounding the Tide defense with his ability to keep plays alive as the Aggies scored the game's first 20 points.

"No moment is too big for him," coach Kevin Sumlin said of his remarkable redshirt freshman.

And no defense or venue too tough, apparently.

"If you're around him every day, I don't think it bothers him that much," Sumlin said.

The Aggies had been 1-10 against top-ranked teams with the only previous win coming 30-26 over Oklahoma in 2002, but Manziel and Sumlin have entered the SEC with speed and swagger -- and fit right in.

"They played a tremendous game and certainly outplayed us," Tide coach Nick Saban said.

Alabama managed a second-shot national title after losing to LSU just over a year ago in the regular season but seems a longshot to do it again. Alabama would have secured a spot in the SEC championship game with a victory and only Western Carolina and Auburn remaining.

"Two of the three national championship teams that I coached lost a game," Saban said, counting one at LSU. "This team still has an opportunity to win the West and go to the SEC championship game and win a championship. There's still a lot for this team to play for."