QB Josh Huepel isn't spectacular against the Aggies, but good enough to keep the Sooners perfect. (AP)

Oklahoma coach Bob Stoops warned the Sooners about the outcome.

"I told our players last week, there was a good chance, we were going to go down to the final series in this game so just be prepared," Stoops said "I think it's good to be in these types of games. You grow and learn from it.

"You just hang in there to the end and find a way to make a play. It shows how much character and poise this team has."

Marshall's first career interception came with 7:18 left in the game, completing a comeback from a 10-point, fourth-quarter deficit that allowed the Sooners (9-0, 6-0 Big 12) to remain the nation's only major team with a perfect record.

"I was just running until somebody tackled me," Marshall said. "I really was just trying to hold onto the ball and not let somebody strip me. That's what it was, it was Sooner magic."

With a Kyle Field attendance of 87,188 roaring from the outset, Sooners quarterback Josh Heupel finally got the Sooners going in the final period.

"We're always confident," Heupel said. "On the sidelines and in the huddle, we kept saying, `we're going to make a play.' We were just talking about staying in rhythm, stay confident on that last drive. We expected good things to happen."

With Texas A&M ahead 31-21, Heupel -- just 2-for-8 on third-down conversions at the time -- made three straight third-down plays leading to a 2-yard touchdown run by fullback Quentin Griffin with 7:43 left.

Moments later, Marshall gave the Sooners the lead when he stepped in front of a pass by A&M's Mark Farris and weaved his way into the end zone to give Oklahoma its first victory in College Station since 1903.

The Aggies (7-3, 5-2) had a final chance to win the game when they took over on the Sooners 44 with 1:33 left, but Farris' fourth-down pass completion fell five yards short of a first down and Oklahoma took over with 36 seconds left. The Sooners ran out the clock and breathed a collective sigh of relief.

"The bottom line is that we had a chance to win the game and didn't get it done," Farris said. "That's why they are the No. 1 team in the country. There was a lot of ups and downs in the game. That is the way big games go. They did a good job of putting pressure on me but our offensive line held and I was only sacked twice."

Oklahoma should remain first in next week's Bowl Championship Series standings, which determine who plays in the BCS' national title game in the Orange Bowl on Jan. 3.

The Sooners still have games remaining against Texas Tech and Oklahoma State before a likely spot in the Big 12 title game on Dec. 2.

After coming so agonizingly close to victory, the Aggie dropped to 0-9 against No. 1 ranked teams. The last time A&M played a No. 1 team was 1977 when it lost to Texas 57-28.

"When you play the No. 1 team in the nation and play them close, that tells you what kind of drive and character we have on this team," Ja'Mar Toombs said. "I can walk out of the locker room holding my head high because I'm proud to be on a team that does not quit."

A&M hadn't even made it close against the top ranked teams until Saturday, losing the eight games by an average score of 41-12.

Big plays by Texas A&M's defense, including two interceptions off Heupel, helped the Aggies to their 31-21 lead. Heupel, among the top Heisman Trophy contender, finished 28-of-42 for 263 yards.

The Aggies capitalized on a blocked punt, interception and fumble to set up three scoring plays for a 17-10 halftime lead, marking the first time this season that Oklahoma had trailed at the half.

It looked even bleaker for the Sooners when the Aggies went ahead 24-10 with nine minutes to play in the third quarter on a 1-yard run by Toombs, which followed Heupel's second interception of the game.

But Oklahoma finally got a break when Sooners cornerback Michael Thompson intercepted a pass by Mark Farris, leading to a 27-yard field goal by Tim Duncan following a holding penalty by OU lineman Frank Romero that wiped out a 4-yard TD run by Josh Norman.

A short 42-yard drive took only three plays to make it even tighter as Griffin scored on a bull-like 21-yard run up the middle and Heupel passed to tight end Matt Anderson for the 2-point conversion and the Sooners trailed 24-21 with 14:46 to play.

Toombs kept the Aggies ahead when he broke off four players and carried three defenders into the end zone on his 27-yard TD run that put the Aggies ahead 31-21.

With the score tied 10-all, Jonte Buel stripped Sooners receiver Andre Woolfolk of the ball and safety Michael Jameson recovered at the Oklahoma 39, setting up a 4-yard TD pass from Farris to Robert Ferguson.

Ferguson caught the ball in the end zone behind Thompson, who also had two first half pass interference calls that helped the Aggies. Ferguson caught eight passes for 105 yards.

The Aggies got the first break when Jay Brooks broke through and blocked Oklahoma's first punt of the game, his career fourth block, giving A&M a first down at the Sooner 12-yard line.

An 11-yard pass interference gave the Aggies a first at the 2, setting up Farris' 2-yard touchdown keeper with 9:14 to go in the first quarter.

It was Oklahoma's narrowest victory margin of the season. The Sooners beat Kansas State 41-31.

A one-point victory would have satisfied Marshall.

"We've got a pretty good defense, but I guess you'd call it a no-name defense," Marshall said. That's why we wanted to come through and win this game. When you come through in a situation like this in the fourth quarter, you see what your team is made of."