Updated

Ryan O'Reilly scored 3:55 into overtime, as his shot trickled through the legs of Florida goalie Jose Theodore, and the Colorado Avalanche rallied for a 4-3 win over the Florida Panthers on Wednesday night.

Paul Stastny tied it late in regulation, and Peter Mueller scored twice — his first goals since April 2010. Mueller has been dealing with concussion-like symptoms the last two seasons, missing all of 2010-11 and a good portion of this season.

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.

Florida had two breakaway chances in the extra period, but were turned away by Jean-Sebastien Giguere

Stephen Weiss, Marcel Goc and Tomas Kopecky scored for the Panthers, who lost their seventh straight road game. They haven't won in Denver since Jan. 2, 2003.

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 3 minutes left when he tapped in his rebound.

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 may 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 back after sitting out because of the concussion.

Mueller is 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," Avalanche coach Joe Sacco said.

Before the game, the Panthers said they will be without veteran defenseman Ed Jovanovski for perhaps as 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.

NOTES: The Panthers sent forwards Evgenii Dadonov and A.J. Jenks to the Carolina Hurricanes for forwards Jon Matsumoto and Mattias Lindstrom. ... The Avalanche activated D Shane O'Brien from the injured list. To make room on the roster, the team placed F Brandon Yip on waivers. ... D Jan Hejda (groin) sat out for Colorado.