CALGARY, Alberta -- Playing in his 100th NHL playoff game, Corey Perry had belief that the Anaheim Ducks could battle back from a three-goal deficit against the Calgary Flames.

"You never say never," said Perry, who scored at 1:30 of overtime to lead the Ducks to a 5-4 win over the Flames on Monday at the Scotibank Saddledome. "You just keep pushing shift after shift, just get pucks to the net. We found a way tonight, and that's all that matters."

Perry also had an assist and finished with a plus-5 rating, an Anaheim playoff franchise record, as the Ducks took a commanding 3-0 lead in their Western Conference first-round playoff series with the Flames.

Perry's shot from a bad angle in overtime hit Calgary goalie Brian Elliott and then deflected off defenseman Michael Stone's backside and in.

"I just tried to get it at the net," said Perry, who credited linemates Nate Thompson and Rickard Rakell for their work on the game-winning marker. "I knew (Thompson) was in front because (Rakell) made a good play along the wall to get it over to me. We stuck with it all night, getting pucks to the net, and it worked out for us."

Shea Theodore scored his first two NHL playoff goals for the Ducks, while Thompson had a goal and two assists. Nick Ritchie also scored, while Hampus Lindholm, Kevin Bieksa and Rakell had two assists each.

In relief of Anaheim starting goalie John Gibson, Jonathan Bernier stopped all 16 shots he faced to pick up the win.

"I'm just going shot by shot," Bernier said. "I could feel obviously that we were gaining momentum. The building was loud, and then we just chipped away. I think we found our game mid-second (period) and we just kept pushing, pushing, and we found a way to win."

Gibson gave up four goals on 16 shots before being relieved by Bernier at 8:33 of the second period.

Sean Monahan had a goal and an assist for the Flames, while Stone, Kris Versteeg and Sam Bennett also scored. Mikael Backlund and T.J. Brodie recorded two assists apiece.

"When you get to overtime, it's anybody's ballgame," said Calgary coach Glen Gulutzan, whose team won 33 straight games in the regular season when leading after two periods. "We've been so good throughout the season at protecting leads. For whatever reason, we couldn't hold onto this one."

Elliott made 22 saves.

The Flames opened the scoring with a power-play goal by Monahan at 2:10 of the first period. Troy Brouwer passed from behind the net to Monahan, who quickly one-timed the puck past Gibson.

Calgary took a 2-0 lead on another power-play goal at 9:18. Monahan had a couple of great chances in front before Versteeg lifted a point-blank shot past Gibson.

The Ducks pulled within a goal at 15:33 of the first period when Ritchie swatted a shot from the slot past Elliott, who gave up a big rebound after stopping Antoine Vermette's initial attempt.

Stone wired a long-range shot past Gibson at 4:34 of the second period.

Mark Giordano's point shot deflected into Anaheim's net off Bennett's skate at 8:33 for Calgary's third power-play goal of the game. That gave the Flames a 4-1 lead.

After Theodore snapped a shot past Elliott at 19:11, the Ducks nearly cut the deficit to one goal when Jakob Silfverberg rang a shot off the crossbar as time expired in the second period.

"It puts them within two and they come out in the third with a push," said Giordano. "I thought we had some chances again in the third, but not enough. We didn't sustain enough zone time. I felt like we stopped making plays, which was the reason why we were dominating the first half of the game. In key pressure situations, the good teams still make the plays, and they were pressing. We should have had more chances than we did."

Thompson redirected a shot by Lindholm past Elliott at 11:14 of the third before Theodore scored his second of the game just over four minutes later to tie the game and send it into overtime.

NOTES: Ducks D Cam Fowler skated on Monday for the first time since sustaining a sprained knee during a 3-1 win at home over Calgary on April 4. ... Ducks D Sami Vatanen missed his second straight playoff game with an upper-body injury, while RW Jared Boll and RW Ondrej Kase were healthy scratches for Anaheim. ... C Curtis Lazar, C Freddie Hamilton, D Dennis Wideman and G John Gillies sat out for Calgary. ... D Mark Giordano was originally credited with Calgary's fourth goal that eventually went to C Sam Bennett in the second period. It would have been Giordano's first playoff goal since April 17, 2007, a span of exactly 10 years.