The first two goals were on the Flyers' suddenly dominant power play. Leino's goal was the 13th straight scored by the Flyers in the last three games, a club playoff record.
The victory gave the Flyers a two-games-to-none lead in the Eastern Conference finals, with Game 3 to be played Thursday in Montreal.
Leighton made 30 saves and became the second goalie in Flyers history to register back-to-back playoff shutouts. The first was Hall of Famer Bernie Parent, who did it against Toronto in 1975.
The Flyers won the Stanley Cup that season.
After failing to win more than five in a row in the regular season, Team Resilient has won six straight playoff games since falling into an almost-impossible three-games-to-none hole against Boston in the conference semifinals. The Flyers became the third team in NHL history to accomplish that comeback feat - and the first to do it while facing a 3-0 deficit in Game 7.
Despite their latest win, the Flyers talked about how the team seemed out of sync for most of the night.
"We had one good player out there, and obviously we know it was Leighton," said defenseman Kimmo Timonen, who helped set up the first goal and blocked a game-high four shots. "The rest of us, we were average. And that's not good enough. We won the game, but now we kind of have to realize, it's hard to get to this point - and we can't slip any games away because we're not doing our jobs as well as we can."
Added Timonen: "We can enjoy this, but we've got to go back to work, because that wasn't pretty."
The Flyers were 2 for 4 on the Joe Mullen-coached power play after going 2 for 6 in Game 1; Montreal was 0 for 4 for the second consecutive game.
"Special teams," Montreal coach Jacques Martin said, "were the difference."
After a listless first period, the Flyers steadied themselves and took a 2-0 lead when the irrepressible Gagne knocked in a rebound with 4:11 left in the second period, making the Flyers 2 for 2 on the power play.
Leino's digging in front set up the goal, and after his shot was turned aside by Jaroslav Halak, Gagne swatted in the loose puck for his sixth goal in six games since returning from a broken foot.
It gave the Flyers 12 straight goals - briefly tying a franchise playoff record set in 1980 - since they remarkably erased the 3-0 deficit against Boston in Game 7. They beat Montreal, 6-0, in Game 1 of the conference finals.
A short time after Gagne's goal, the fans erupted in Montreal's singsong chant.
"Ole . . . ole-ole-ole . . . ole . . . ole."
"A dirty goal," Gagne said. "We crashed the net there. We had a couple of whacks at it. I was on the side of the post. I think I fell just before that. That's why I was right there when the puck came right on my blade. I just had to push it in."
A giveaway by defenseman Braydon Coburn led to a great opportunity for Montreal's Mike Cammalleri, but Leighton made a chest save of his close drive with about 2:40 left in the second period.
"Mich-ael Leigh-ton . . . Mich-ael Leighton," the orange-clad crowd chanted.
The first period was eerily similar to Sunday's, when the Flyers were badly outplayed but built a 1-0 lead.
Just like in Game 1, the Flyers left the ice after 20 minutes with a one-goal lead because of Leighton's brilliance and a power-play goal.
Briere, Mr. May, continued his sizzling playoff run by blasting a high, well-placed right-circle drive past Halak's glove on the short side.
Halak left an opening that was a few inches wide. That's right where Briere put it after taking a pass from Claude Giroux 4:16 into the game. It was his ninth goal in the playoffs, tops on the team, and it marked the fourth straight game in which he had scored.
"I'm just trying to ride the wave," Briere said.
Giroux, on a give-and-go feed, collected his 14th playoff point on the goal.
"It was a great play by Claude," said Briere, who made a nifty move to avoid defensemen Hal Gill and Josh Gorges. "When I got the puck in the slot, I knew that especially Gill and Gorges like to block shots. So I faked the shot and tried to take a step to the side so they wouldn't be in my view to block the shot."
Montreal dominated the opening period, outshooting the Flyers, 16-6. But Leighton stood tall, making eight of his 16 saves on power plays.
Montreal lost despite winning 56 percent of the face-offs and outshooting the hosts, 30-23.
"We did certain things much better tonight," Martin said. "I can't blame the effort. We just need to bring some solution to our special teams."
The Flyers are 16-0 in series in which they have won the first two games. Then again, Boston was 16-0 in series in which it won the first three games, a warning that this conference final is far from over. Montreal overcame a 3-1 series deficit against powerful Washington in Round 1.
Contact staff writer Sam Carchidi at 215-854-5181 or email@example.com.
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