Oklahoma tight end Jermaine Gresham will miss the rest of the season after having surgery to repair torn cartilage in his right knee.

Coach Bob Stoops said that doctors determined during an arthroscopic surgery Tuesday that they needed to stitch together the cartilage in Gresham's knee. Stoops said Gresham will need five months to recover.

The 13th-ranked Sooners are already reeling from the loss of Heisman Trophy-winning quarterback Sam Bradford, who sprained his shoulder in a 14-13 loss to BYU and will be out at least two weeks.

Gresham was a second-team All-America pick last season and had been considered a top NFL prospect before returning for his junior year.

THIS IS A BREAKING NEWS UPDATE. Check back soon for further information. AP's earlier story is below.

NORMAN, Okla. (AP) _ Heisman Trophy winner Sam Bradford had just been helped to the sidelines with an injured shoulder when Oklahoma's players headed in for halftime of their game against BYU.

Bradford was being checked out by the team's medical staff, which would later determine he had a sprained shoulder and would be out for a while. Fellow team captain Brody Eldridge was getting fluids after his first ever start as the Sooners' center. And star tight end Jermaine Gresham was already hobbled with an injured right knee.

The Sooners were a somber group Saturday night.

"It was a total morgue," offensive coordinator Kevin Wilson said Tuesday. "It was a concern. I was a cheerleader for 10 minutes: `We're winning. Open your eyes. Get a little spunk here. Let's go! This is why we practice hard, for great games. Let's go!'"

It's been a difficult start for Oklahoma, which plummeted 10 spots to No. 13 in The Associated Press' college football poll Tuesday after that game, a 14-13 loss to BYU.

Some may have seen it coming: The Sooners had to replace four starting offensive linemen this season, only to see projected starter Ben Habern and backup Brian Lepak both get injured at the center position. Eldridge was moved to center from his spot as backup tight end and then Gresham was hurt four days before the season opener.

Backup linebacker Mike Balogun was ruled ineligible by the NCAA, only to have his backup, Tom Wort, suffer a season-ending knee injury less than a week later. And now Bradford is out for two to four weeks.

"After a start like that, it really just humbles you," guard Brian Simmons said.

On Tuesday, the Sooners were holding their breath as Gresham _ like Bradford, an NFL prospect who returned for another season _ had arthroscopic surgery to determine the extent of the cartilage damage in his right knee.

Gresham was Oklahoma's top returning receiver with 66 catches for 950 yards and 14 touchdowns last season. He needs only five more TDs to tie the school's career record of 31 set by Mark Clayton.

"The possibility could be that there's a piece of something that's loose in there that can be removed and he'll be able to resume playing after a couple of weeks," Sooners coach Bob Stoops said. "If they have to stitch and repair the cartilage, then that is a five-month recovery, which would mean he would be out for the season, but his long-term health would be fine."

If there's a silver lining, Oklahoma's veteran players can reflect on how they dealt with a string of bad luck in 2006: the dismissal of quarterback Rhett Bomar and two other players because of NCAA rules violations, a blown call on an onside kick that led to a loss at Oregon and then running back Adrian Peterson breaking his collarbone.

Simmons said he recalled Peterson's injury when Bradford went down.

"I think this is a little more different because it's Sam and Jermaine. That's a lot," Simmons said. "I'm not saying that they're better or more talented than A.D. It's slightly different.

"I will say when he went down, I was devastated. I was just like, `Oh, man.' But we actually went undefeated without him that season."

Oklahoma was 7-0 without Peterson, winning the Big 12 title before losing in his return against Boise State in the Fiesta Bowl.

Wilson said he was discouraged that the Sooners offense didn't rally around each other at halftime and instead sat silently in the locker room. He said it was quarterback Landry Jones, the redshirt freshman who made his college debut while replacing Bradford, who finally broke the ice.

"He was the only guy in the locker room talking at halftime," Wilson said. "He's the guy that gathered them up, and a guy that hasn't said much."

To salvage their chances of winning the Big 12 and national titles, the Sooners will have to shake off the setbacks and create their own good luck. The first chance for a turnaround is Saturday, when Oklahoma hosts Idaho State of the Football Championship Subdivision.

"In the end, our guys know. We expect whoever's out there to do well," Stoops said. "You have to move forward. Just like other injuries, someone else has to step up and play. That's what a team does, and our guys are aware of that."