Redskins running back Clinton Portis is being called "very, very doubtful" for Sunday's game against the Broncos. Portis suffered a concussion last week. He did not attend practice on Wednesday. "I had him in my office this morning and he was still ... you could tell that he wasn't quite 100 percent," coach Jim Zorn said. "We're not going to mess around with any concussion. He does have a concussion."