Eden Praire (AP)—At the end of a long, difficult season, Brett Favre's status for the finale is again in doubt.

After overcoming so many injuries and other personal adversity to play every week of his storied 20-year career, Favre has been too beat up to play in two of the last three games. He got knocked out of the other one.

The Vikings want him to give it one more try and start Sunday at Detroit, but by NFL concussion rules he first must be cleared by the team’s medical staff — and time is running out.

Interim coach Leslie Frazier said Thursday that Favre hadn’t passed the first stage of the standard post-concussion testing. There’s also a conditioning component to receiving clearance to return, if Favre can prove he’s symptom-free and functioning normally again.

“We’d love to see him play,” Frazier said. “There’s no question about that.”

Though he said he wouldn’t rule out Favre, Frazier also said Saturday would probably be the “cutoff” for Favre to pass the tests.

Favre has not been available to reporters since Dec. 20, when he made a surprise start on a sprained shoulder against Chicago, but got slammed to the cold turf during a sack by the Bears and left for good in the second quarter with the injury to his head.

“It was one of the few times that I kind of went blank there for a while in my career,” Favre said after the game.

He said, in explaining his decision that night to take the risk of playing, he wanted one more chance to play in front of Minnesota’s fans.

“It has been a great run,” Favre said. “I think my stubbornness, hardheadedness and stupidity at the time has enabled me to play for 20 years and play the way I’ve played. It’s just the way I’ve always approached it.”