In the most anticipated game of the day one, Canada came from two down to overturn their opponents in the second and third period at the WinSport Arena in Calgary.

Nelli Laitinen was assisted by Sofianna Sundelin to open the scoring within three minutes; and the Finns doubled their tally four minutes later thanks to Minnamari Tuominen.

Late goals in the second period turned the tide for Canada thanks to two in less than a minute from Jamie Rattray and Marie-Philip Poulin.

Erin Ambrose gave the hosts the lead for the first time early in the third period, but Elisa Holopainen equalised five minutes later.

Sarah Fillier responded immediately to put Canada 4-3 up and Brianne Jenner put the game to bed in the final minute.

"Obviously we weren't pleased with our play for the first 20 minutes," said Canadian head coach Troy Ryan.

"We talked at intermission about the little details. 

"We wanted to do a better job on our face-offs and build a line of scrimmage on puck drop. 

"There's no need to motivate this group, it's just some fine tuning and in-game adjustments."

Defending champions the United States join their northern neighbours at the top of Group A after beating Switzerland 3-0.

In the first period, Brianna Decker scored within five minutes, assisted by Kendall Coyne Schofield and Hilary Knight.

Decker returned the favour in the second period, setting up Schofield for the second, before Grace Zumwinkle finished the scoring late in the second.

Finally, the Czech Republic thumped Denmark 6-1 to top Group B.

Alena Mills and Dominika Laskova made it 2-0, 13 minutes into the game.

Josefine Persson would score Denmark's only goal, but the Czechs retained their two-goal cushion late in the first period thanks to Vendula Pribylova.

After an uneventful second period, Mills started the final 20 minutes immediately with a fourth goal.

Kristyna Patkova made it five and Mills got her hat-trick minutes from the end.