Kyle Kosier leaves field with leg injury

OXNARD, Calif. -- Cowboys starting left guard Kyle Kosier limped off the practice field on Wednesday morning with an apparent leg injury.

Kosier was injured in the first practice here during team drills and walked to the locker room with head athletic trainer Jim Maurer. Former Cowboys lineman Nate Newton of ESPN 103.3 FM in Dallas reports that the injury is a sprained knee. Kosier will have an MRI this afternoon.

Also, linebacker Jason Williams limped off with a leg injury of some sort after falling down while covering a pass. (UPDATE, 12:32 -- Williams has returned to practice)

It's the second injury to an offensive linemen this week. The Cowboys lost starting right tackle Marc Colombo on Monday with a knee injury. Colombo underwent surgery on Tuesday in Dallas to clean out his knee.

Montrae Holland replaces Kosier in the lineup.

Losing Kosier means two things for the Cowboys: The backup center and starting guard is gone.

The No. 3 center is Phil Costa.

Kosier played just three games in 2008 after suffering a fracture to his right foot. But he came back strong last season and didn't miss any games.

He's in the last year of his contract, which pays him a base salary of $2.9 million.