CALGARY — Johnny Gaudreau's overtime winner in a 6-5 victory over the Philadelphia Flyers returned the Calgary Flames to first place in the NHL's Western Conference.

Trailing 5-3, Calgary's Sean Monahan and Rasmus Andersson scored in the final 68 seconds of regulation to tee up Gaudreau's winner 35 seconds into extra time Wednesday

"Huge win," Gaudreau said. "We stuck with and found a way to play a little bit harder in the third and get the two points.

"Ending up finding a couple of greasy goals there in the last two minutes and winning in overtime. The building was electric."

Calgary (20-10-2) vaulted over the Nashville Predators, which are at home Thursday to the Vancouver Canucks, into top spot in the conference.

The Flames beat the Preds 5-2 on Saturday, but Nashville had pulled ahead with a win over the Ottawa Senators.

Philadelphia (12-13-4) continues to toil in the Eastern Conference's bottom tier.

The Flyers are 2-2-1 since the Nov. 30 firing of general manager Ron Hextall. Chuck Fletcher replaced him four days later.

Gaudreau missed the final six and a half minutes of the first period after taking a knee to the head from Philadelphia's Radko Gudas, but was back on the bench to start the second.

With the Flames driving the net in 3-on-3 overtime, he scored the winner on a second rebound.

Monahan's two goals gave the centre a team-leading 20 in 31 games. That's the fastest the 24-year-old has reached that mark in his NHL career.

Mark Giordano and Sam Bennett also scored for Calgary, which improves to 11-3-2 at home. Matthew Tkachuk had four assists.

"It is a resilient group," Calgary head coach Bill Peters said. "We had a lot of chances. We gave up more than we liked. We were fortunate to get enough action at the net late and were rewarded."

David Rittich earned the win with four saves in relief of Mike Smith, who stopped 10 of 14 shots through two periods. Peters says he didn't pull Smith out because of his performance.

"I got news he wasn't right after 40 (minutes). It was real late. Just before we went on the ice, I was told Ritter was going in," Peters said. "Smitty wasn't quite feeling right. Tried to play through it and couldn't."

After sitting out two previous games with a lower-body injury, Sean Couturier had two goals and an assist for the Flyers.

Philadelphia also got goals from Travis Sanheim, James van Riemsdyk and Dale Weise. Captain Claude Giroux collected two assists. Goalie Anthony Stolarz made 35 saves in the loss.

The Flyers killed off four Calgary power plays in the third period, but couldn't hold off the Flames pressure in the end.

"The penalties set the table for the two tying goals," Flyers coach Dave Hakstol said. "That kills the bench, kills your energy.

"But even at 4-2 and a two-goal lead in the third period, we're still trying to make fancy plays that end up in turnovers in the neutral zone, when we should be locking down a game.

"Not even close to the kind of third period that we needed."

Couturier's second goal scored shorthanded at 11:10 of the third gave the visitors a two-goal cushion.

But with Rittich pulled for an extra attacker, Monahan drew the Flames even with seven seconds left in regulation.

Andersson scored his first career NHL goal with a one-timer from the point at 18:52.

The Flyers scored three goals in a 1 minute 48-second span to lead 4-2 in the second period, but Monahan's power-play goal at 10:13 had Calgary trailing by one heading into the third.

"You don't want to have a game like that when you're chasing, but you stick with it and obviously we got the two points," Monahan said.

Notes: Giordano returned to the lineup after serving a two-game suspension for kneeing Minnesota Wild captain Mikko Koivu on Dec. 6 . . . Calgary centre Mikael Backlund sat out a third game after taking a hard hit from Wild defenceman Mathew Dumba in the same game.