DALLAS — Sooners quarterback Sam Bradford reinjured his right shoulder early in the game and isn't likely to return for No. 20 Oklahoma against No. 3 Texas on Saturday.

Bradford, the reigning Heisman Trophy winner, was jerked down by unblocked Longhorns cornerback Aaron Williams while running backwards trying to get away from the defender on Oklahoma's second drive.

Williams got Bradford by the waist, but the quarterback landed on his shoulder and began writhing in pain right away. Backup Landry Jones, who has started three games this season, replaced Bradford.

"Just similar to the last one." Stoops said on TV at halftime. "Don't know anything other than that."

When asked if Bradford would return, the Oklahoma coach said. "I don't believe that'll happen."

Bradford missed a month with a sprained AC joint in his right shoulder. He returned last week and threw for 389 yards against Baylor.

Jones was 12 of 23 for 130 yards in the first half in relief of Bradford as the Sooners led 6-3 at halftime.

Bradford, who was 2 of 6 for 77 yards, eventually started testing his range of motion and few minutes later tried to throw the ball. But it was clear he couldn't get any zip on it and was in pain.

Bradford tried holding his helmet with his right hand but it appeared to cause him discomfort and switched it to his left hand.

Soon, he was standing on the sideline without his helmet. Bradford would stand near the offensive huddle but would stay toward the back during timeouts. After the break, he had taken off his jersey and pads and stood on the sideline in a T-shirt.

Bradford decided to pass on the NFL draft last spring to take another shot at winning the national title after the Sooners lost in last season's championship game to Florida.

In 2008, Bradford threw for 4,720 yards and led the nation with 50 touchdown passes. He likely would have been one of the top quarterbacks taken if he had left school

Bradford's chances of winning a second straight Heisman ended in the opener against BYU when he was driven to the turf, injuring his throwing shoulder. Bradford missed three games before returning against Baylor.