MINNEAPOLIS - Who is Joe Webb?

First off, he's the answer to this question: Who will the Minnesota Vikings start at quarterback Sunday night against the Eagles if Brett Favre can't play?

And that leads us to the next question: Who is Joe Webb?

The gist: Webb is a rookie from Alabama-Birmingham, a sixth-round pick the Vikings intended to convert to wide receiver. Vikings coaches scuttled that plan in training camp, however, after discovering Webb's arm was just as impressive as his legs and freaky athletic ability. For the evidence of the latter, go to YouTube, where video of the 6-foot-3 Webb jumping a stack of seven tackling dummies made the rounds last spring (http://www.youtube.com/watch?v=p9PsUH1fmJk).

Webb was due to make his first NFL start on Monday night until Favre, who hadn't practiced for two weeks because of a sprained right shoulder, talked his way into the lineup. Favre lasted a little more than a quarter before Chicago's Corey Wootton planted him into the FieldTurf at TCF Bank Stadium. Favre left with a concussion, and Webb finished the Vikings' 40-14 loss to the Bears.

Struggling in the wind and snow, Webb completed 15 of 26 passes for 129 yards with two interceptions. But he also showed impressive elusiveness by gaining 38 yards on six runs, with a 13-yard touchdown.

"He got out of a lot of different situations using what God blessed him with, his feet," wide receiver Percy Harvin said. "He had a lot of mixed feelings, and he handled himself very well."

Webb said he understood the last-minute switch to Favre.

"Brett's a future Hall of Fame quarterback, and whenever he feels like he's able to play, he's going to play," Webb said. "There's nothing that's going to hold him back."

Except, of course, the NFL's new protocol on concussions. Before Favre can practice or play, he must pass baseline tests and be cleared by an independent physician as well as the team doctor.

Interim coach Leslie Frazier confirmed on Monday that Webb will start if Favre is unavailable. Not that Frazier has much choice. Tarvaris Jackson (toe) is on injured reserve, and backup Patrick Ramsey joined the team on Thursday.

Many NFL scouts projected Webb, with his huge hands, as a wideout even after he became the first player in NCAA history to pass for 2,000 yards and rush for 1,000 in consecutive seasons at UAB. Webb worked out at wide receiver at the Senior Bowl. The NFL did not invite him to the annual scouting combine, but Webb bettered the top combine marks in the broad jump and 20-yard shuttle run at an on-campus workout for pro scouts.

Though Webb opened training camp at wide receiver, Brad Childress, then the head coach, switched him to quarterback after giving Webb a chance to throw in drills. Webb's 48-yard touchdown run in an Aug. 22 exhibition game at San Francisco opened more eyes.

Fearing Webb wouldn't clear waivers if they tried putting him on the practice squad, the Vikings traded veteran Sage Rosenfels to the Giants to keep Webb on the active roster.

"There's no way you can cut this guy and put him on the street, because someone's going to take him," offensive coordinator Darrell Bevell said. "He's got too many skills to be able to work with."

Webb quarterbacked the scout team until three weeks ago, when the Vikings installed a package of plays for him against Buffalo. Webb returned the opening kickoff 30 yards, then lined up as a wideout on the first play from scrimmage. But he strained a hamstring covering a punt later in the quarter, ending his day. Last week, Webb completed 2 of 5 passes for eight yards after relieving Jackson in a 21-3 loss to the Giants.

Now, unless Favre makes another miracle recovery, the starting job is his. Bevell said he wishes Webb ran a little less - "Quarterbacks get hit," he said - but that threat will be important if Adrian Peterson remains hobbled by knee and thigh problems.

"I can't make them miss like he can," Favre said of Webb.

But Webb is still a mistake-prone rookie. And unlike the 5-9 Vikings, the Eagles have something to play for.

"Regardless of whether you put him at quarterback or at wide receiver, he's raw at it," Bevell said. "He's in the beginning stages. You have to learn and continue to work. Now the best decision is to have him at quarterback, and let's see if he can do it."