VANCOUVER - Johnny Gaudreau knows that Saturday night could have turned out much differently. That's just life in the NHL's new 3-on-3 overtime format.

The diminutive winger scored on a quick shot at 3:03 of the extra period as the Calgary Flames defeated the Vancouver Canucks 3-2.

Gaudreau had the puck on his stick in the Vancouver zone seconds before the winner, but was dispossessed by Vancouver forward Brandon Sutter, who was poised to send Daniel Sedin in on a breakaway.

But Sutter in turn lost it to Calgary defenceman Dennis Wideman, and the puck found its way back to Gaudreau, who made no mistake in beating Ryan Miller.

"Definitely nerve-wracking," Gaudreau said of 3-on-3 OT. "With so much time and space and ice, one costly turnover or mistake and that's the game. You've got to be smart out there. You have to be strategic about it, but it's fun."

Calgary head coach Bob Hartley said that Gaudreau, who also had two assists, wants to be a difference-maker every time he's on the ice.

"You can't teach to be great in big moments. This guy's got it," said Hartley. "Every time I see that he has the puck on his stick I feel that we have a chance to win. That's who he is and that's how he plays."

Dougie Hamilton and Sean Monahan also scored for the Flames (1-1-0), while Jiri Hudler added two assists of his own.

Jonas Hiller made 28 stops in his first start of the season for Calgary, which lost its home opener 5-1 to Vancouver on Wednesday.

"I thought that this was the Calgary Flames," said Hartley. "Third period, we were skating well. I thought our puck possession was real good. Then in OT, well, just open the floodgates and just watch."

Hiller made a couple of big saves in the extra period before Gaudreau's winner, including a glove stop on Sedin.

"It's kind of like an all-star game," said Hiller. "You've got to be pretty much ready for anything. It's kind of fun, but at the same time it's definitely not the kind of game you want as a goalie."

Bo Horvat and Jared McCann, with his first in the NHL, replied for the Canucks (1-0-1), who got 35 saves from Miller.

Down 2-1 after two periods, the Flames started to press and tied it at 8:49 of the third when Monahan scored his first of the season.

"We quit getting the puck deep. We turned it over," said Canucks head coach Willie Desjardins. "We'd go cross-ice or we'd dump to their (defence), and they kept coming after us. When you do that eventually they are going to get something."

McCann gave his team a 2-1 lead at 11:33 of the second, taking a pass from Jannik Hansen and ripping a shot high over Hiller's glove in just his second NHL game.

The 19-year-old forward nearly jumped out of his skates in celebration, smashing into the boards with excitement before getting mobbed by teammates.

"I almost blacked out to be honest," said McCann. "It was a great feeling, but obviously it would have been nice to end the way we wanted."

Vancouver trailed 1-0 after the first, but tied things up at 2:03 of the second on the power play when Horvat scored his first after some nice work at the blue line by rookie defenceman Ben Hutton.

The Flames, who beat the Canucks in six games in the first round of last season's playoffs, opened the scoring exactly five minutes into the first period on the power play.

Gaudreau took a pass at the side of the Vancouver net before feeding Hamilton, who roofed a shot on Miller from the face-off dot for his first point with the Flames since being acquired from Boston Bruins in the off-season.

"Our guys responded well," said Hartley. "I thought (Hiller) gave us a huge game in net, as did Miller on their side. It was great goaltending on both parts and both teams battled hard."

Notes: Vancouver defenceman Alexander Edler missed the game because of illness. Yannick Weber took his spot in the lineup. ... Calgary was 10-20-4 when trailing after 40 minutes last season.

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