OXNARD, Calif. -- A respectful rivalry is simmering between two of the Cowboys’ young stars.

Or you could call it a healthy chippiness.

One of the treats of this training camp has been watching running back DeMarco Murray and inside linebacker Sean Lee butt heads.

They’re a couple of intense dudes who have tasted some success and are determined to take the next step in their careers. They consider competing against each other an excellent developmental opportunity.

It just isn’t always friendly on the field, as much as they enjoy each other’s company once practice is over.

“I think it’s a good thing,” Garrett said. “They’re competitive guys. They understand the tempo we want to practice with. They understand we’re on the same team, but they’re going to compete against each other in the drills they have.

“It goes to their spirit, to how much they love the game and how they go about it.”

Murray is on a mission to “set tone” every time he has the ball in his hands. That’s resulted in a concussion for cornerback Teddy Williams and more than a few collisions with Lee.

There isn’t supposed to be any tackling during Cowboys practices, but Lee got sick of Murray lowering his shoulder into him during 7-on-7 drills the other day. After Murray popped him, Lee expressed his frustration by tossing the tailback to the ground.

“That’s part of the deal,” said Lee, who got the best of Murray in blitz pickup drills Monday afternoon. “He’s run me over, I’ve knocked him pretty hard a few times. That’s part of competition.”