Paul Stastny tied it late in regulation, and Mueller scored twice -- his first goals since April 2010. Mueller has been dealing with concussion symptoms the last two seasons, missing all of 2010-11 and a good portion of this season.
"It feels unbelievable," Mueller said. "I wish I could explain it more how good it feels to get that one out of the way. Everyone has been so supportive through this whole process. What a night to cap it off."
The Avalanche caught the Panthers on a rush late in overtime, with O'Reilly shooting a puck right at Theodore, who couldn't corral it. Just like that, the Avs had an improbable win, especially after falling behind 3-1 early in the third period.
"A huge character win for us," said O'Reilly, who leads the team in scoring but netted his first career regular-season overtime goal. "It shows that no matter what, we're in each game."
Florida had two breakaway chances in the extra period, but were turned away by Jean-Sebastien Giguere.
"It's frustrating," Florida defenseman Brian Campbell said. "We have to find a way to win that in overtime. I know we don't want to be in that situation in the first place, but it would have been nice to get something going there."
Kopecky's goal 20 seconds into the third period gave the Panthers a 3-1 lead, but it wouldn't last. Mueller scored his second of the game, and Stastny tied it with just over three minutes left when he tapped in his rebound.
The pivotal moment of the game might not have been on a goal but on a penalty-kill by the Avalanche. After Jay McClement was given four minutes for high sticking, the Panthers had a chance to potentially seal the game with a goal. But the Avs weathered the storm and kept it a one-goal game.
"Big kill for us," Avalanche coach Joe Sacco said. "They really dug in. That was obviously a big part of the game."
Weiss scored an unusual goal in the second period that stood up after a lengthy video review. As the center skated in, he was tripped and tumbled to the ice. While sliding along the surface next to the puck, Weiss ran into Giguere's leg, pushing his pad out of the way, and opened the door for the puck to roll into the net.
At first, it appeared on replays that the puck might have hit Weiss' glove and been pushed in. But referee David Banfield conferred with replay officials, and the goal was confirmed. It was Weiss' first goal since Dec. 5, and it came in his 600th career game.
Mueller is starting to get his timing back after a lengthy layoff. This was his fourth game after sitting out because of the concussion. He's also beginning to resemble his old scoring self again, gobbling up a rebound and beating Theodore with a wrist shot in the second period.
In the third, Mueller scored again -- firing a slap shot off a pass from O'Reilly. To help reduce the possibility of another head injury, Mueller has been wearing bigger shoulder pads, a helmet that loops around his ear to provide more protection, and a tinted visor that cuts down the glare from the arena lights.
"I think I'm becoming the player I used to be," Mueller said.
Goc put the Panthers on the board first when he redirected the puck past Giguere on the power play late in the first period. It was his fifth goal of the season.
Tomas Fleischmann was back in the building where he was a steady scoring threat for the Avalanche last season. But this place also is filled with harrowing memories.
Nearly a year to the day, Fleischmann experienced shortness of breath following a morning skate. Later that day, he was diagnosed with two blood clots, one in each lung. He was sidelined for the rest of the season, and then signed with Florida in the offseason. He has quickly fit in with the Panthers and has been a reliable goal scorer.
"I'm just happy for him, happy he's healthy and happy he's having a good year," Sacco said.
Before the game, the Panthers said they will be without veteran defenseman Ed Jovanovski for perhaps two months after he underwent surgery to fix a broken hand. Jovanovski was injured during a fight in a game against the Boston Bruins on Monday.
The 35-year-old Jovanovski has two goals and six assists in 43 games this season.
- The Panthers sent forwards Evgenii Dadonov and A.J. Jenks to the Carolina Hurricanes for forwards Jon Matsumoto and Mattias Lindstrom.
- Giguere earned his 11th victory, equaling his total from last season with Toronto.