ARLINGTON, Texas - Coming off a trip to the national title game, and having Heisman Trophy winner Sam Bradford back under center, Oklahoma had grand expectations this season.

One jarring hit might’ve changed everything for the Sooners — and BYU.

Bradford sprained his throwing shoulder in the closing seconds of the first half. A mediocre performance by his backup, a questionable decision by coach Bob Stoops and a late meltdown by OU’s defense let Max Hall and the 20th-ranked Cougars pull out a 14-13 victory Saturday night in the first college football game at Cowboys Stadium.

The severity of Bradford’s injury won’t be known for days. But there’s no doubt this dents his bid to repeat as the Heisman winner and it throws Oklahoma’s championship hopes for a loop.

“This loss hurts,” Sooners offensive lineman Brian Simmons said. “But the last two or three years, the national champion has had one loss. There’s still a chance for us to accomplish our goals.”

For Hall and BYU, this victory could be a springboard for their most memorable season in decades. It turns them into a top candidate to be the latest BCS busters from the Mountain West and it should shove Hall to the fringe of the Heisman discussion.

“Where it’s going to rank and all that, I’m not certain, but I know there are a lot of people who are going to benefit from the way these kids played today,” Cougars coach Bronco Mendenhall said.

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Hall was 26 of 38 for 329 yards and two touchdowns, with two interceptions and four sacks. What matters most is that when he had a chance to win it, he pulled off a 16-play, 78-yard drive, converting on a fourth-and-4 and throwing for a 7-yard touchdown to a wide-open McKay Jacobson in the back of the end zone with 3:03 left in the fourth to put BYU ahead for good.

“Unbelievable,” said Hall, a nephew of former Cowboys quarterback Danny White. “For us to come out and pull off a win is a special night. I’ll never forget it.”

Neither will Sooners fans.

They’ll wonder if an offensive line featuring four new starters was to blame for BYU linebacker Coleby Clawson plowing into Bradford with a hard, clean hit that left them both landing on Bradford’s shoulder.

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And they’ll wonder whether Stoops played it safe when — as it turns out — they needed him to get a little risky.

It was midway through the fourth quarter with Oklahoma leading 10-7 and backup quarterback Landry Jones had just gotten stuffed on third-and-goal from the 1. Stoops let Jones go for it on fourth down, but the redshirt freshman failed to get the snap off in time. The penalty pushed OU back to the 6, so Stoops opted for the field goal and a 13-7 lead, knowing a touchdown would put them behind.

“I did (think about going for it),” Stoops said. “That’s on us as coaches.”

After BYU’s go-ahead score, the Sooners still had a chance to win.

Jones got them to the Cougars’ 32, then they were pushed back by a false start penalty on new right tackle Cory Brandon. It was his fifth penalty and the ninth of the game for the OU line, although two were declined.