Dallas Cowboys first round pick Morris Claiborne underwent an MRI on his sore right knee after Friday's afternoon practice, ESPN Dallas reported. The cornerback tried to practice during the session but trainers decided to hold him out. Coach Jason Garrett said the team does not think the injury is serious and that the MRI was a precaution. Claiborne felt soreness in the knee Wednesday and got treatment for it Thursday. "He had a little twinge there in his knee and our trainers thought it would be best to give him the afternoon off," owner Jerry Jones said. "At this time we are not concerned."