NORMAN, Okla. (AP) -- Chris Brown started out three spots behind Adrian Peterson on Oklahoma's depth chart at running back. He never thought he'd be the key to a big win down the stretch.

Brown, the fourth-string tailback, ran for two fourth-quarter scores and Paul Thompson threw for a career-high 309 yards and two touchdowns as the No. 17 Sooners rallied to beat Texas Tech 34-24 on Saturday night.

"The things we've gone through, whoever's in there we're going to win with them," Thompson said. "That's our mind-set. We've got confidence. If something happens no one's freaking out."

With their top two tailbacks injured, the Sooners' 15-game streak with a 100-yard rusher -- the longest in the nation -- was snapped. But Brown still gave them plenty of pop on the ground.

He broke through two tacklers, spun and then cut toward the middle of the field for a 40-yard score that put Oklahoma up 27-24 with 12:51 left. He then added a 2-yard plunge with 2:21 remaining that iced the game and provided sweet revenge for the Sooners (8-2, 5-1 Big 12), who lost at Tech last season on a disputed 2-yard run by Taurean Henderson as time expired.

"It felt really good. We knew the last drive that we had to push it in," said Brown, who finished with 84 yards on 16 carries. "A field goal would have left them enough time to drive it down and score."

The only previous playing time for Brown was fourth-quarter mop-up duty in one game.

"It just shows that we're a diverse group. We've got different ways to handle situations," Sooners coach Bob Stoops said. "What I appreciate is they never flinch at it."

Texas Tech (6-5, 3-4) missed a pair of field goals in the fourth quarter to aid Oklahoma's comeback.

With a chance to tie the game at 27, Alex Trlica was wide left from 28 yards out with 9:18 to play on a drive that started at the Oklahoma 35 after Joe Garcia recovered Manuel Johnson's fumble. Tech's Chris Parker and Johnson appeared to hit helmets on the play, and Johnson had to be carted off the field and taken to a waiting ambulance.

Stoops said Johnson was responsive in the ambulance but would remain hospitalized overnight.

On Tech's previous drive, a 42-yard Trlica field goal was negated by a false start penalty, and he missed wide left from five yards farther back.

Oklahoma had averaged 207 yards rushing in its first three games without Peterson, the 2004 Heisman runner-up. But this time, neither Peterson (collarbone) or his backup, Allen Patrick (right ankle), were available.

Brown said he never really expected to be a factor until after Patrick's injury last week. And even then, he thought Gutierrez would be the primary back. But down the stretch, it was Brown that the Sooners turned to.

"It was real exciting. We were in a close game and they chose me to be out for the remainder of the game and finish it off. That really touched me and made me want to perform to my top ability," Brown said.

The win kept Oklahoma in the race for the Big 12 title. Following Texas' loss at Kansas State on Saturday, the Sooners need to win out and have the Longhorns lose at Texas A&M to claim the Big 12 South.

"We're not out of it," Thompson said. "There's some things that have got to happen but we're not out of it."

Thompson and Malcolm Kelly picked up the slack until Brown got going.

Thompson was 24-for-31 and Kelly had a career-high 11 catches for 153 yards. The two connected on a 40-yard touchdown pass 10 seconds before halftime to ignite a run of 24 straight points for the Sooners.

"That touchdown was big to give us that spark going into the locker room," Stoops said. "And Malcolm Kelly, what catches he makes. He's just incredible."

Back-to-back Red Raiders penalties contributed 20 yards and a first down to the drive, and Thompson cashed in with a floating spiral down the left sideline after a pump fake.

Texas Tech opened a 24-10 lead with 1:43 left in the first half when Antonio Huffman intercepted Thompson's pass and returned it 54 yards down the sideline for a score. It was Thompson's first interception in 99 pass attempts dating back to the Texas game -- Oklahoma's last loss.

Graham Harrell completed 26 of 48 passes for 250 yards and two touchdowns to Robert Johnson -- from 30 yards and 6 yards.

"I thought both teams were really tough. It was an extremely physical game," Tech coach Mike Leach said. "Both teams really wanted to win the game. This game here was a hard-fought deal of inches and we just came up a few inches short when it comes down to it."