CALGARY, Alberta -- Corey Perry scored at 1:30 of overtime to give the Anaheim Ducks a 5-4 win over the Calgary Flames at the Scotiabank Saddledome on Monday, providing the Ducks with a 3-0 lead in their Western Conference first-round playoff series.

Perry's shot from a bad angle hit Calgary goalie Brian Elliott and then deflected off defenseman Michael Stone's backside and in to lead the Ducks to a come-from-behind victory.

Calgary led 4-1 late in the second period.

Shea Theodore scored his first two NHL playoff goals for the Ducks, who now have a commanding lead in the best-of-seven series.

Nate Thompson had a goal and two assists for Anaheim, Nick Ritchie also scored, and Hampus Lindholm, Kevin Bieksa and Rickard 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. 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 each had two assists.

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 4:31 of the second period to make it before 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 19:10, 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.

But Thompson and Theodore scored third-period goals for Anaheim to tie the game and send it into overtime.

NOTES: Anaheim RW Corey Perry suited up for his 100th NHL playoff game. ... 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.