Chris Cooley has been ruled out of Friday night's preseason opener vs. Pittsburgh, head coach Mike Shanahan said.

Cooley continues to be slowed by knee soreness, Shanahan said.

The veteran tight end, entering his eighth season with the Redskins, sat out Wednesday's training camp practice at Redskins Park.

"There is concern," Shanahan said. "The knee is sore, but hopefully it keeps on getting better."

Cooley, a two-time Pro Bowler, has participated in camp off and on. He missed several days last week but returned to take part in individual drills Monday and Tuesday of this week.

Fred Davis is seeing the bulk of reps in Cooley's place, followed by Logan Paulsen. Mike Sellers, the Redskins' long-time fullback, is competing for playing time at tight end as well.

The Redskins made a roster move at the tight end position on Wednesday morning, signing Derek Schouman, a fifth-year pro out of Boise State, and releasing undrafted rookie Kevin Gidrey.

Offensive lineman Artis Hicks has also been ruled out of Friday's preseason game. Hicks suffered a mild concussion earlier in camp.