Clinton Portis will sit out this Sunday's game against the Dallas Cowboys, head coach Jim Zorn said.

Portis continues to recover from the concussion he suffered on Nov. 8 in a game against the Atlanta Falcons.

"Clinton is going to continue to be monitored and continued to be checked, but we're not going to play him," Zorn said.

Portis, who leads the Redskins with 494 rushing yards this season, has not practiced with the team since before the injury. He is still experiencing some "blurriness" when he tries to run, Zorn said.

"I want to see him practice and I want to see him have those days where when he practices he doesn't have any of the residual problems," Zorn said. "Right now, he can't even practice, so we'll keep him out."

Ladell Betts will start for the second game in a row in place of Portis. Backups Rock Cartwright and Quinton Ganther should also see action.

Betts rushed for a season-high 114 yards on 26 carries in last Sunday's 27-17 win over the Denver Broncos.

Asked how Portis's status impacts him, Betts replied: "You get to be the man on first, second and third down, because before that, it was pretty much only on third down. Now I know that I get to play a full game, so it's a little bit different mindset."

And it won't change the offensive game plan vs. Dallas, Zorn added.

"We didn't change the run game necessarily to accommodate Ladell," Zorn said. "We ran our stuff, and what he did was push up into the hole and fight for yardage."

Zorn indicated he was leaning toward allowing Portis to travel with the team to Dallas.

"Just to keep him involved--but that [decision] hasn't been finalized in my mind," Zorn said.

Meantime, Albert Haynesworth sat out practice for the second day in a row on Thursday as he continues to rest a sprained ankle.

Haynesworth is expected to be a game time decision, Zorn said.

"Albert is coming along and the swelling is starting to come down," Zorn said. "We're going to continue to work him."

Mike Williams is showing improvement in his return from a sprained ankle. He is also a game time decision.

If Williams plays, then he would serve in a supporting role at right tackle or right guard.

"I'm just looking for Mike to just be active," Zorn said. "I'm not going to put him in as a starter."

Stephon Heyer remains the starter at right tackle and Chad Rinehart is the starter at right guard.