OXNARD, Calif. -- Cowboys starting cornerback Morris Claiborne didn't participate in the walkthrough practice Thursday morning because of a sore left knee, raising concerns about his availability for Friday night's preseason game at Oakland.
Claiborne jammed his knee in Tuesday's practice and tried to get some work in Wednesday. But he said the knee felt tight and the training staff didn't want him to risk further injury. It's doubtful Claiborne will play.
Also, rookie wide receiver Terrance Williams missed practice as he recovers from a concussion. Williams ran sprints with some other injured players during the Wednesday walkthrough. Williams most likely will miss the Raiders game.
Kevin Kowalski (knee), Jeff Olson (concussion), Ray Dominguez (shoulder), Nate Livings (knee), Demetress Bell (conditioning), Matt Johnson (foot), Alex Albright (back), Ryan Cook (back), Jay Ratliff (hamstring) and Anthony Spencer (knee) did not practice and won't play against the Raiders.
Update: The Cowboys released Olson after the walkthrough practice. He did some work in the rehab session Thursday morning.