He seemed lost, in a daze like never before. Balancing on crutches in the visitor's locker room of FedEx Field on Saturday evening, Adrian Peterson didn't really know what to say.

He had yet to undergo the MRI that would later reveal major ligament damage in his left knee, an ACL tear with MCL problems also likely.

But it was clear from Peterson's blank expression that he had seen his future flash before his eyes.

He seemed depressed. Confused. A little scared even.

Before even saying a word, Peterson stared into the carpet and let his lips rumble with exasperation.

No one in the Vikings' locker room would say it. But the vibe was apparent, that one monstrous unanswerable question hovering in the air like stale cigar smoke: Had we seen the last of Adrian Peterson?

Not in the sense that Peterson never will play again. No one in the Vikings organization has the stomach to even consider that fate at this early stage of the injury. But if and when Peterson can return to action, will this injury sap him of his trademark explosiveness?

Did this one fluke play in a meaningless game late in a terrible season signal a premature decline for one of the most electric playmakers in team history?

It's far too early to foster much of an educated guess. But the fact these questions are being asked should give one a sense of the situation's gravity and a better understanding of the suffering Peterson seemed to be experiencing Christmas Eve.

After all, if you thought the hit he took from DeJon Gomes looked bad, with Peterson's knee buckling and turning in all the wrong directions, you should have felt the pain that came with it.

"Was it as bad as it looked? Yeah," Peterson said. "Especially initially, the pain was very severe."

Now comes the mental agony, too, that paralyzing uncertainty of what's next, the curiosity surrounding the recovery timetable.

The range of possibilities is wide. Yes, the most optimistic Vikings fans will gravitate toward the belief that this is merely a minor setback for a star as tough as Peterson.

They'll immediately reference Wes Welker. After all, the Patriots receiver tore both his ACL and MCL on Jan. 3, 2010. Yet, miraculously he was back playing full-time by the middle of the preseason 8 1/2 months later.

Less than two years removed from that injury, Welker appears to be better than ever, leading the NFL with 116 receptions and having set a Patriots single-season record for receiving yards (1,518 and counting).

That has to provide a nice ray of hope for Peterson, right?

"I'm going to try to stay as positive as I possibly can," he promised Saturday.

Still, the pessimist line is swelling with concrete examples that validate the worst fears.

Remember the catastrophic knee injury quarterback Daunte Culpepper suffered at Carolina early in the 2005 season?

At the time, he was a 28-year-old budding superstar coming off a Pro Bowl season during which he set a new NFL record for yards from scrimmage.

Then, after one fluke play, he plummeted from game-changing to ordinary.

Yes, Culpepper stuck around the NFL for the next four seasons. But he was never the same, physically weakened and just a little uncertain of his knee's strength.

After that injury, Culpepper started only 20 games for three different teams over four seasons and was last seen playing for the Sacramento Mountain Lions of the United Football League.

So yeah, the naysayers see Welker's impressive recovery pushed to the center of the conversation but quickly raise you a Culpepper, a Keith Millard, a Terrell Davis, a Jamal Anderson, a Cadillac Williams and a Robert Edwards, all players whose blown knees stole their dynamic abilities right in their prime.

Davis, like Peterson, was in his fifth NFL season at the time he blew his knee out in 1999.

A former MVP and two-time Super Bowl champ, he was never a difference-maker again, plagued by knee problems plus additional injuries and playing only 13 more games in 2000 and 2001 before calling it quits.

No wonder Peterson seemed so crestfallen Saturday, struggling to come to grips with what had just happened. He knew the injury was bad. Perhaps, even worse, he understood it will take an incredibly long time to determine just how bad.

What a year.

On Sept. 10, on the Vikings' first road trip this season, Peterson was given a seven-year contract extension worth $100 million. The future seemed bright.

Fifteen weeks later, on the final trip of 2011, he absorbed a career-threatening knee injury, suddenly lined up for surgery, a grueling rehabilitation process and an immediate future with so much doubt attached.