GANGNEUNG - Four-time defending women's hockey champion Canada stretched their Winter Olympics win streak to 21 games on Sunday, blanking the Olympic Athletes from Russia 5-0 in their Pyeongchang Games opener.

It was Canada's first Olympic game since edging the United States 3-2 in the 2014 final, with 2018 captain Marie-Phillip Poulin netting a last-minute equaliser and over-time gold decider in that thriller. Rebecca Johnston and Melodie Daoust each scored twice and Haley Irwin tipped in a Johnston slap shot for Canada in Gangneung. "We had to play a really good game to get this," Johnston said. "We can't bring less than our A game. They had a lot of energy."

Goaltender Ann-Renee Desbiens made 18 saves for Canada, which battled through a scoreless first period before pulling away. "I was a little excited at first but then I settled down," Desbiens said. "It's always nice when we can put a lot of pucks in the net. It's a boost of confidence going forward."

The world champion Americans were tested in another round-robin opener but Monique Lamoureux-Morando and Kendall Coyne netted second-period goals to rally the US women past Finland 3-1 despite 39 saves from Finnish goaltender Noora Raty. "It was a good start for us," said Lamoureux-Morando. "We know we are going to face some tough goalies."

If Canada beats Finland and the Americans defeat the Russians in group play Tuesday, both North American powers would clinch semi-final berths before renewing their rivalry in a round-robin concluder Thursday. Americans have won eight of the past 10 world titles, beating Canada in each final, but their lone Olympic crown came in 1998 at Nagano.

Flag-waving Russian supporters chanted "Russ-i-a" several times during the contest, backing a young OAR squad with only six prior Olympians. Finland's Venla Hovi opened the scoring with 5.8 seconds remaining in the first period to seize momentum from the Americans.

"No panic," Coyne said of the US locker room emotions after the opening period. "We stuck with the game plan. We've been in this position before. It's nothing we can't handle. Let's get out there and get this game."

The Americans answered on Lamoureux-Morando smacking in a rebound to equalise and just 2:31 after that Coyne swatted a cross-ice pass from Hilary Knight just under the crossbar for a 2-1 US edge. "She put it in my wheelhouse," Coyne said. "I put it in the back of the net."

The Americans denied two Finland power-play chances in the third period and Dani Cameranesi's empty-net goal with 13 seconds remaining clinched matters. "Usually power play is our strength," Raty said. "We can't take so many penalties if we want to beat the US or Canada." Rikka Valila, 44, became Finland's oldest Winter Olympian and the oldest Olympic women's hockey player.