EDEN PRAIRIE, Minn. - Leslie Frazier counted Brett Favre out once before. He is not about to do it again.

On Friday, the Minnesota Vikings listed Favre as doubtful for Sunday night's game against the Eagles because of a concussion, leaving the door open for the 41-year-old quarterback to play.

A week ago, the Vikings listed Favre as out for a game against Chicago with a sprained right shoulder. He surprisingly was upgraded to questionable the day of the game and ended up starting against the Bears, a development that didn't sit well with Bears coach Lovie Smith.

"No out with Brett Favre," Frazier said with a grin. "Will not use that term."

Favre led the Vikings on a touchdown drive to open the game Monday night but didn't make it through the second quarter after being sacked by Corey Wootton. Favre's head slammed off the frigid turf of TCF Bank Stadium, and he was knocked woozy.

Frazier said earlier this week that no Viking had played in a game the week after suffering a concussion, but conventional wisdom rarely applies when it comes to Favre.

"Last week, I came in here with the expectation I was going to be the [backup], and two hours before the game I'm not," said Patrick Ramsey, who was signed last week to bolster the depth at quarterback. "I don't think with a guy like [Favre] you can ever know."

Star running back Adrian Peterson is listed as questionable with the thigh bruise that kept him out of the game against the Bears. Safety Tyrell Johnson (knee) is out, and starting safety Madieu Williams (concussion) is questionable.

Favre, the NFL's iron man, had made 297 consecutive starts before that streak ended two weeks ago. Most figured he would miss the Bears game as well after not throwing a pass in practice all week. But head athletic trainer Eric Sugarman said Favre woke up Monday morning feeling much improved and talked his way into the starting lineup.

He completed 5 of 7 passes for 63 yards with a touchdown and an interception before leaving the game.

But a concussion is a far different matter. The NFL and the players union have increased the attention paid to head injuries in recent years.

The team has given Favre, who did not practice all week, a symptom test every day to measure his progress, and he has to reach a certain baseline level before he can be cleared to play.

Even then, he'd still need to pass a cardio test that checks whether he has any negative side effects when his heart rate is elevated.

If Favre cannot play, rookie Joe Webb will make his first career start. Webb went 15 for 26 for 129 yards with two interceptions and a touchdown rushing in the 40-14 loss to the Bears. He took all the snaps with the first-team offense in practice this week.

"It helped me out with my timing with the receivers and getting timing down and communication with the O-line," Webb said of his work this week. "I haven't been in the huddle with those guys the whole year."

Webb was the No. 3 quarterback for most of the year, but top backup Tarvaris Jackson went on season-ending injured reserve last week with turf toe.

"I think he's gotten better in some areas, and we're tailoring some things to his strengths, and I think he'll play even better than he played last week," Frazier said. "The big thing is being on the road, in a very tough environment to play in, getting past that initial series. That's going to be a big one for him."