"It was nice to score. [Anderson] is not an easy guy to score on so, yes, you have to be happy about that but it was more important for us to get the two points," Weiss said.
T.J. Galiardi and Matt Duchene both scored for Colorado with less then a minute left in regulation to force overtime. Chris Stewart and Paul Stastny also had goals for Colorado. Duchene netted another goal the second period.
Scott Clemmensen, starting in place of injured Panthers goalie Tomas Vokoun, made 29 saves. Vokoun is recovering after he was hit in the head by Florida defenseman Keith Ballard's stick during a bizarre on-ice accident Monday night. Vokoun received stitches on his ear but had no other medical problems.
"The bottom line is we got the win," Clemmensen said. "It was a seesaw battle. Fortunately, we had a hot shooter and he made the difference for us."
Ballard was involved in another scary incident on Wednesday. Charging toward the net with less than a minute left in overtime, Ballard slid toward the net and appeared to collide with Anderson, whose head hit the goal post.
"He wasn't running the goalie," Florida captain Bryan McCabe said. "He either lost an [skate] edge or was hit. He hit him for sure but didn't mean to. He was on his butt. How can you stop?"
Ballard wasn't available to speak with reporters after Wednesday's game.
Anderson remained on the ice for a few minutes after the collision and was replaced by Peter Budaj. Colorado's Adam Foote pounced on Ballard afterward and a scuffle ensued behind the net. Ballard was penalized for goaltender interference.
"I haven't talked to our trainer yet but he obviously took a hard hit there at the end of the game in overtime and he wasn't able to finish the game," Colorado coach Joe Sacco said. "I don't know any more than that."
Facing his former team for the first time, Anderson stopped 39 shots. Anderson, who spent three seasons with the Panthers, was coming off a 33-save effort in Colorado's 3-0 win over the Tampa Bay Lightning on Monday.
Duchene added a goal with 52.6 seconds left in regulation to make it 5-4. With 16 seconds remaining, Galiardi tied it at 5-all.
"It's tough," Duchene said. "You battle back so hard, you played so hard in the third and the second period. I think we maybe deserved a little better fate."
Stastny scored at 4:49 in the third period to make it 4-3. But at 7:41 in the third, Moore poked the puck into the net during a power play to put the Panthers up 5-3.
Horton's power-play goal gave Florida a 4-2 lead with 3:39 left the second. Horton beat Anderson with a shot from the high slot for his eighth goal.
Colorado scored its first of the night 5:52 into the second period. Clemmensen stopped the initial shot from Duchene, but Stewart tipped in the puck. However, Weiss followed that goal with his third of the night -- a wrist shot at 8:16 in the second that made it 3-1.
Weiss' first hat trick came on Jan. 13, 2007, in Florida's 7-3 win over the Washington Capitals. After his third goal Wednesday, play was delayed as caps were cleared from the ice.
Duchene's first of the game came on the power play and cut Florida's lead to one at 11:19 in the second period.
Weiss opened the scoring with a power-play goal with 3:55 remaining in the opening period. With Marek Svatos in the penalty box for tripping, Weiss tipped in the puck. With 1:14 left in the first, he put in a rebound with a wrist shot to make it 2-0.
The Panthers were the only NHL team Anderson had never faced. ... The Avalanche, who had dropped eight of 10 before Monday's win, are in the midst of a five-game trip that will wrap up Dec. 7 in St. Louis. ... Florida recalled forwards Jeff Taffe and Mike Duco and goalie Alexander Salak from AHL Rochester and reassigned forwards Shawn Matthias and Steve MacInytre.