Patrik Laine led the way with two goals, including the winner with 5:50 left, and an assist for Finland. Sebastian Aho potted a goal and two assists, and Aleksi Saarela had a goal and an assist. Antti Kalapudas and Julius Nattinen got the other goals. Tournament scoring leader Jesse Puljujarvi and Olli Juolevi had three assists apiece.
Laine's 6-5 goal came on a one-timer during a Finnish two-man advantage with Jake Virtanen serving a double minor and Joe Hicketts off for delay of game.
"This was the most amazing game of my life so far," said Laine. "I hope that we will keep going and hope that we can win more."
Mitch Marner scored twice for Canada, and Travis Konecny, Dylan Strome and Lawson Crouse added singles. Captain Brayden Point had two assists.
"We wanted to come out and show them what we had," said Crouse. "We did that. Our goal was to try to score the first goal and we did that. Things went from there. Obviously it didn’t end the way we wanted."
In a bold move by coach Jukka Jalonen, Finnish starting goalie Veini Vehvilainen was replaced by Kaapo Kakhonen halfway through the game after surrendering three goals on 10 shots. Mackenzie Blackwood, though also not in prime form, went the distance for Canada. Shots favoured Canada 34-29.
"It was actually a pretty weird game," said Finnish captain Mikko Rantanen. "First we were losing 2-0 and then we were scoring, they were scoring all the time. We scored one more than them, so we’ll take the win and we have to be happy with that."
It was always going to be tough for this year’s Canadian squad to live up to the accomplishments of the 2015 champions with Connor McDavid, Max Domi, and Sam Reinhart, who helped the team to a perfect record in Montreal and Toronto.
It is a monumental disappointment for the former champions. The Canadians never quite found their game in the preliminary round, losing twice for the first time since 1998.
"It was tough," said Hicketts, the only returning defenceman from 2015. "We had a younger group. We didn’t start the way we needed to. Last year, we came out of the gate and we were firing on all cylinders. This year, we kind of stumbled through the first couple of games. You know what? We found our game tonight, and the sad thing is we probably deserved better. I thought we played our hearts out.'
The Finns last won gold in 2014 with a dramatic 3-2 victory over host Sweden on Rasmus Ristolainen’s overtime goal. They will improve on last year's seventh-place finish, but have to get through archrival Sweden to make the final.
"I think it will be a pleasure to beat those guys," said Laine. "I hope that we will play as well as now."
The Canadians have now failed to medal at three of the last four World Juniors. Canada’s worst stretch ever was going medalless from 1979 to 1981. Canada won its first gold in six years on home ice last year, defeating Russia 5-4 in a thriller in Toronto.
The passionate Hartwall Arena crowd of 13,016 ranged from Finnish fans waving huge cardboard cut-outs of Puljujarvi’s head to Canadian supporters dressed in beaver costumes.
The game got off to a high-tempo, physical start. Canada grabbed a 1-0 lead on a skillful play at 5:21. John Quenneville sent a clever backhand pass from behind the goal line to Konecny, who in turn beat Vehvilainen with a backhander to the stick side.
Finland got its first power play when Thomas Chabot put the puck over the glass in his own end, but was unable to break through despite peppering Blackwood with shots.
The Canadians jumped into a 2-0 lead at 10:59. Vehvilainen was unable to smother a loose puck in his crease and Strome banged it home.
Finland’s top guns got a big momentum-building goal with 11 seconds left in the period. After a faceoff in the Canadian end, with some help from Puljujarvi, Aho got the puck along the boards and sent it to Laine at the top of the faceoff circle. His powerful one-timer, which he models on Alexander Ovechkin and Steven Stamkos, squeezed past Blackwood.
"He’s a good player and he’s got a good shot," said Virtanen. "It’s tough to see that one go in."
The Finns tied it up at 6:18 of the second period on a Canadian defensive error. Chabot stumbled and fell over inside his own blue line, enabling Kalapudas to scoot in unmolested and whip one over the goalie’s glove.
Carrying the play, Canada stormed the Finnish crease about eight minutes into the middle frame, but Vehvilainen hugged his right post, and video review confirmed the puck did not cross the goal line.
Just seconds afterwards, Crouse gave Canada a 3-2 lead. After defenceman Vili Saarijarvi gave the puck away, Virtanen set up Crouse for a snap shot from the right faceoff circle that beat Vehvilainen on the glove side.
At this point, Kaapo Kahkonen took over from Vehvilainen. His only previous appearance at these World Juniors was in an 8-3 win over Slovakia.
"Actually, I didn’t expect that," said Juolevi. "But I kind of understand that they want to wake our team up. I think it was pretty smart. Kaapo made some good saves in the second period and also the third period."
The Espoo Blues netminder looked confident coming in, and stoned the Canadians on multiple chances. He got a standing ovation from the Finnish fans when he sprawled with his left arm and robbed Brendan Perlini of a sure goal by his left post.
With Perlini off for slashing, the Finnish power play came to life. Puljujarvi fed Saarela on the left side and his bad-angle shot from the goal line sneaked past a befuddled Blackwood at 15:44.
The Finns went up 4-3 with 2:43 remaining in the middle frame. As the Finns buzzed around the Canadian zone, Juolevi set up Saarela for a one-timer that Blackwood stopped, but Nattinen golfed the rebound over him.
At 3:14 of the third, Canada finally got one past Kahkonen on the power play. Coming in from the right side, Point dished it sweetly to Marner, and he cut to the middle and flipped a backhand over Kahkonen's glove.
Finland responded with the 5-4 marker just 1:07 later. Taking a long pass from Laine, Puljujarvi bulled in from the right side and couldn't get it past Blackwood, but Aho was there to stuff in the rebound.
Canada struck right back to tie it up with the man advantage at 5:07. On another Point set-up, Marner picked up the puck in the faceoff circle and executed a nice toe drag before zipping it high glove.
Trailing 6-5, the Canadians pulled Blackwood for the extra attacker with 1:05. But despite a brief flurry, they couldn't cash in and their reign came to an end.
"Finland scores a lot of goals, and you wish them all the best because they’re the team that beat you out," said Hicketts. "That being said, there are so many great nations, and that just proves it in the quarter-finals. You look at what Denmark did to Russia, forcing them to overtime. You’ve got six, seven powerhouse hockey nations now, and anyone can win on any given night."