Clinton Portis is active and expected to play in Sunday night’s game against the Dallas Cowboys.Portis has a sprained knee that sidelined him for practice last week.Head coach Jim Zorn said that Portis might play a limited role due to the fact that he missed practice time.Three hours before kickoff on Sunday, Portis was on the field testing his injured knee. He appeared to be able to cut on the knee without any noticeable pain.Among those watching the warm-ups were head coach Jim Zorn, assistant head coach-running backs Stump Mitchell, director of sports medicine Bubba Tyer, head athletic trainer John Burrell and physical therapist Larry Hess.They appeared to be taking particular note of Portis’s ability to block pass-rushers on the injured knee.After the workout, Portis huddled with team officials on the sidelines to discuss his availability.Television cameras filmed the meeting, but they were quickly ushered away to keep the secrecy of Portis's status intact.Portis suffered the knee injury in the days following the Redskins’ 23-6 loss to the Pittsburgh Steelers on Nov. 3. The injury worsened during the bye week.He entered Sunday’s game listed as questionable