Source: Claiborne sprains MCL
Team officials didn't believe the injury was serious, but scheduled Claiborne for an MRI on the sore right knee after Friday's practice.
"He had a little twinge there in his knee and our trainers thought it would be best to give him the afternoon off," team owner/general manager Jerry Jones said. "At this time we are not concerned."
Coach Jason Garrett said Claiborne suffered the knee injury during Wednesday's practice, and after an off day, the knee didn't feel right during the early portions of Friday's practice. Claiborne missed close to two hours of practice time.
"He got treatment on it (Thursday)," Garrett said. "His knee flared up a little bit on him, so he tried to go in the early part of practice and we took him out of it."
Claiborne wasn't the only Cowboys player taken out of practice Friday. Third-round pick Tyrone Crawford, a defensive end, had to leave with a calf injury.
Outside linebacker Anthony Spencer also missed Friday's practice and won't participate on Saturday as he recovers from a hamstring injury.
"It's just a strain," Spencer said after Friday's walk-through. "We'll see how it feels in the morning."
Victor Butler received first-team snaps in place of Spencer at Friday's practice.
"You hate to see one of your teammates in pain," Butler said of Spencer. "Even today with Anthony Spencer down, he's going to be on the sidelines coaching me up, that's the kind of relationship we have. He's a great teammate and an even better guy. When he goes down, I try to step up like he's not even missing."
Spencer, who was franchised at $8.8 million this season, is coming off a career-high six-sack 2011 season. He was also credited with 31 quarterback pressures and eight tackles for a loss last year.
Spencer said recently he's not upset he doesn't have a long-term contract from the Cowboys but feels if he produces this year, something will happen.
The Cowboys are missing two projected starters to the offensive line in Nate Livings (hamstring) and Mackenzy Bernadeau (hip, knee), cornerback Mike Jenkins (shoulder) and backup guards Kevin Kowalski (ankle) and Bill Nagy (ankle) to injuries.
As a result, Garrett is concerned about the offensive line's chemistry being stunted.
"Continuity is always a concern," he said. "Regardless of how much time you play together, you always feel like you want more time, particularly on the offensive line. You'd like to get to that point as quickly as possible, but injuries are a reality in the NFL and you have to deal with them."
Safety Gerald Sensabaugh, who underwent minor knee surgery three weeks ago, passed his conditioning test on Friday and said he expects to practice Saturday.
Tim MacMahon of ESPNDallas.com contributed to this report.