OXNARD, Calif. – Receiver Dez Bryant and guard Mackenzy Bernadeau worked with the starters in Sunday’s walkthrough.

Bryant, who hamstring tightened up in the middle of team drills during Saturday’s practice, will be a game-time decision for Monday night's preseason opener against the Oakland Raiders. The Cowboys will determine whether Bryant will play a series or two after he warms up before the game at Oakland-Alameda County Coliseum.

"This early in camp we're not going to push hamstrings," owner/general manager Jerry Jones said Saturday. "That's just the policy, and this is exactly why we have the policy. When a player gets a little tightness, then we will be very conservative. The word is conservative, how much he pushes it, and there wasn't any need of him to go through the last drill. And that may be the extent of the precaution."

Coach Jason Garrett and the players were not made available to the media after the walkthrough.

Bernadeau, whom the Cowboys signed in free agency to start at right guard, underwent offseason surgeries on his hip and knee. He missed the first week and a half of training camp, getting his first contact work Thursday. Garrett has said Bernadeau’s availability for Monday would be based on how the guard responded to the practices, and all reports have been positive.

At least seven starters will sit out the preseason opener: receiver Miles Austin (hamstring), center Phil Costa (back), guard Nate Livings (hamstring), nose tackle Jay Ratliff (foot), cornerback Morris Claiborne (knee), outside linebacker Anthony Spencer (hamstring) and defensive end Jason Hatcher (groin).

Claiborne, the team’s first-round pick, practiced Saturday after missing a week with a sprained MCL in his left knee. However, the Cowboys will exercise caution by holding him out against the Raiders.