When the game was finally over, after two missed kicks and two made kicks, three changes of possession and one premature celebration, he walked off the Metrodome turf a winner, the nagging groin injury that has bothered him for weeks feeling just fine.
Walsh drilled his winner after a 39-yarder earlier in overtime was wiped out by a penalty and a 57-yard miss put the Bears in prime position to close it out.
But the normally reliable Robbie Gould missed a 47-yarder for the Bears, leaving the door open for the tireless Peterson. He rushed nine times for 51 yards in overtime alone, including 30 on the final drive that set up Walsh.
''You're at an all-time high because you think you've got a victory, and then you're sitting there waiting for what the call is and you're at an all-time low,'' Peterson said. ''Ultimately we were able to give him another opportunity and he nailed it.''
Peterson's fifth career 200-yard game helped him surpass 10,000 yards for his career in just 101 games, third fastest to do it behind Eric Dickerson and Jim Brown.
"It's been my mindset since I was young to be the best to ever play," Peterson said. "You've got to believe it in order to accomplish it."
Gould's wife gave birth to the couple's first child at 1 a.m. Sunday, and he hopped a flight from Chicago shortly after to get to the game. He said that wasn't an excuse for the miss.
"It was one of the greatest days of my life, and I'm happy for my wife and my little boy," Gould said. "Sorry I couldn't do it for my teammates like I did for my wife this morning."
Alshon Jeffery had 12 catches for 249 yards and two touchdowns for the Bears (6-6), who led by 10 points midway through the fourth quarter. Matt Forte rushed 23 times for 120 yards and Josh McCown was 23 of 36 for 355 yards with two touchdowns and no interceptions for the Bears.
Greg Jennings had seven catches for 78 yards and a touchdown for the Vikings and was halfway up the tunnel early in overtime when Walsh's 39-yard field goal sailed through the uprights for an apparent victory. But Rhett Ellison was flagged for a facemask while trying to block Devin Hester. Jennings had to hustle back on to the field for another play on third down to try to gain some of the yardage back. Peterson was thrown for a 3-yard loss and Walsh's 57-yard field sailed wide left, giving the Bears the ball just across midfield.
Chicago drove into Vikings territory before a decision by rookie head coach Marc Trestman cost it dearly. On second-and-7, the coach elected to let Gould try a 47-yarder. His kick went wide right, giving the Vikings new life.
"We were definitely in range, and I didn't want to at that point in time risk a possible penalty that would set us back, similar to what happened on the other side, or a fumble of some kind," Trestman said. "Something unique."
With their second straight tie looming, Cassel hit Jennings for 17 yards, and the offense then rode Peterson to get Walsh in position for a second try.
He buried this one, capping an unlikely comeback and prompting owner Zygi Wilf to rush the field and hug his players.
Jeffery caught touchdown passes of 80 and 46 yards in the third quarter to give the Bears a 20-10 lead. Vikings defensive back Chris Cook was ejected after the second one for bumping side judge Laird Hayes while arguing for a pass interference call.
But just when Jeffery had seemed to suck the life completely out of the Metrodome, Peterson delivered a jolt against a Bears defense missing six starters. Peterson ran through four tacklers for a 19-yard run that set up an 8-yard touchdown pass from Cassel to Jennings with 7:41 to play in regulation.
The Vikings faced fourth-and-11 from their 8 with under two minutes to play, but Cassel positioned them for Walsh's 30-yard field goal with 24 seconds to play.
Amazingly, both teams still had a chance to win in regulation after that kick. Gould's 66-yard prayer in the final seconds landed in Cordarrelle Patterson's arms in the end zone, but his bid to match the miracle return from Auburn's Chris Davis that beat Alabama on Saturday was stuffed.
When it was all over, the Bears were in no mood to talk about the craziness of the game.
"We've got to put up a win in the win column. ... The standings don't matter if you don't win football games," said McCown, playing again for the injured Jay Cutler.Notes
- Bears DE Julius Peppers had 2 1/2 sacks.
- Bears LB Khaseem Greene had an interception.
- Ponder left in the second quarter with a concussion.
- Patterson had a 33-yard TD run in the second quarter, making him the first Vikings rookie to have score on a return, a catch and a run in the same season.
- Vikings LB Erin Henderson dressed but did not play after it was revealed last week he was arrested for DWI and possession of a controlled substance.