Washington Redskins running back Clinton Portis will miss his second consecutive game as he recovers from a concussion.
Portis hasn't been able to practice since he was injured on a helmet-to-helmet hit during a Nov. 8 game against the Atlanta Falcons.
Ladell Betts is set to start for Portis for the second consecutive week. Betts had 114 yards and one touchdown on 26 carries against the Denver Broncos last Sunday.
Zorn says defensive tackle Albert Haynesworth's status against the Cowboys remains a game-time decision with a sprained left ankle. The coach says Haynesworth is "coming along" and that the ankle's swelling is starting to go down.
NFL Network's Jason La Canfora reports that Haynesworth is expected to play, according to a team source, but the Redskins are discussing dressing an extra defensive tackle -- Anthony Montomery -- for the game. Montgomery has been a starter in previous seasons but has yet to play in 2009.
The Associated Press contributed to this report.