Meghan Agosta-Marciano's power-play goal at 9:27 of the third period broke a scoreless game and led Canada to a dramatic 3-0 win over Finland.
Agosta-Marciano picked up her own rebound in the slot and rifled a wicked slapshot over the glove of Noora Raty.
"We knew from the start that we wanted to be patient and opportunities would come," said captain Caroline Ouellette. "The power-play goal was a real game changer. We kept the pressure, kept on the puck and got a shot off, got a rebound and fired in a rocket of shot."
It was Canada's 17th straight win in women's Olympic hockey and 21st successive win against Finland in the Olympics and World Championships since the IIHF introduced women's hockey to its program in 1990.
Goalie Shannon Szabados, meanwhile, improved her career Olympic record to a perfect 4-0-0 and extended her Olympic shutout streak to 140:14 going back to Vancouver four years ago. She faced only 14 shots tonight.
At the other end, Noora Raty stopped 39 of 42 shots, many great saves, but the story tonight was Finland's team defence. For nearly 50 minutes the Finns checked, blocked, and frustrated Canada in a way it has seldom done in the past.
Indeed, Finland might well have been the better team in the opening period, but Canada's play inside its own blue line was just as impressive.
Canada closes out the round robin with the much-anticipated game against the United States on Wednesday night while the Finns play the Swiss earlier that day.
Both games have important implications. The North American winner will take first place in Group A, while the Finns and Swiss are both 0-2 and want a favourable seeding heading to the quarter-finals.
"Switzerland is huge now," Finnish forward Michelle Karvinen admitted. "We've lost two games and we need to come out with a win. Switzerland aren't a bad team, and they've got a super goalie, so we can't underestimate them. We have to take it as seriously as playing the USA and Canada."
The first period was as evenly played as any between the two nations. The Finns, in fact, had two of the three power plays and moved the puck around with confidence, creating some good scoring chances and giving every indication they were equal to their opponents even though Canada has won all 20 games at the Olympics and Women’s Worlds between the two nations.
It was only in the final couple of minutes that Canada applied some sustained pressure, but the Finns showed remarkable resolve in getting in the way of passing lanes and blocking several shots headed towards goalie Noora Raty.
Canada’s best chance to open the scoring came early in the second period when the team forced a turnover and skated in on Raty on an improbable 4-on-1. But with so many passing options, no one got a clean shot off and the moment was lost.
That proved to be their best chance of the period. Although the Canadians had the puck much of the time, the Finns played brilliant team defence, continuing to block shots and lanes and taking hits to make the smart play.
Shots after two periods were 27-10 in favour of Canada, but Canada’s lack of scoring touch gave the Finns confidence. Emotions boiled over with 4:41 to play. Natalie Spooner, who had been hit accidentally in the head on her previous shift, jammed away at a puck to the side of Raty, but after the whistle all players on the ice scrummed and jostled, the resilient Finns standing up for their goalie, the Canadians frustrated by their inability to penetrate the Finnish defence.
The fallout was another Finnish power play, and Szabados had to be sharp with a couple of good chances.
Canada came out with greater determination to start the third, and Marie-Philip Poulin narrowly missed getting the game's first goal when her short-side shot rang off the post behind Raty. Moments later, Jayna Hefford set Poulin up with a beautiful pass, and Poulin drew a penalty when she was hooked trying to tap the puck in the open side. The Finns, though, killed that short-handed situation off with comparative ease.
A second power play moments later, though, gave Agosta-Marciano the chance to open the scoring.
Emma Nuutinen missed a great chance to tie the game later in the period, and when the puck came down the other way Hefford ripped a high shot over Raty's shoulder at 12:24 to give Canada a much-needed insurance goal.
Rebecca Johnston closed out the scoring, converting a great pass from Poulin on an odd-man rush at 16:36.
"Talking about the competition as a whole," Canadian Jennifer Wakefield suggested, "Switzerland did really well against us last time, and every game has been close so far. It's not really a two-man race any more."