KAMLOOPS, B.C. - For the third time in as many starts against the United States, Emerance Maschmeyer wasn't rewarded for her hard work.

Canada didn't capitalize on a 36-save performance by its goalie. The host team fell 3-1 to the U.S. to open the women's world hockey championship Monday in Kamloops, B.C.

Maschmeyer got the nod over veteran Charline Labonte in part because of her performance at November's Four Nations Cup in Sundsvall, Sweden.

The 21-year-old from Bruderheim, Alta., stopped 30 shots in a 3-2 overtime loss to the U.S. in the final. Her debut against Canada's archrival in the preliminary round there was strong, but the team squandered her 27-save performance in a 3-0 loss.

The world championship opener was a variation on that theme. Canada mustered 23 shots on net and scored one power-play goal in their Pool A game against the defending champions.

"It's always disappointing getting a loss, especially against the U.S.," Maschmeyer said. "It's frustrating, but we're going to use this as momentum and we're going to get them when it counts."

Brianna Decker scored the eventual game winner at 13:55 when Canada's Meaghan Mikkelson was serving a high-sticking minor. Hilary Knight scored even strength and into an empty net in the third. Alex Rigsby earned the win with 21 saves.

Laura Fortino countered with the Canada's lone goal in front of a full house at the 5,400-seat Sandman Centre.

"There's no medal being given out tonight from that game, so we've got to keep going and focus on the next game," said Canadian captain Marie-Philip Poulin.

Finland downed Russia 5-3 in Monday's other Pool A matchup. Switzerland doubled Japan 4-2 and Sweden edged the Czech Republic 3-2 in Pool B.

Canada faces Russia and the U.S. takes on Finland on Tuesday for their second games in as many days to open the tournament.

The top two teams in Canada's pool earn byes to Sunday's semifinals. The bottom two meet the top two from 'B' in Friday's quarter-finals.

The U.S. power play was 44 per cent successful at last year's world championship in Malmo, Sweden, where they scored three goals a man up in the final en route to a 7-5 win over Canada.

The Canadians posted key kills in the first and second periods Monday, but needed another in the third. Decker turned a rebound off a Monique Lamoureux blast from the point into the game winner.

Canada stopped the Americans on a two-man advantage early in the first. Overlapping penalties to start the second had Canada shorthanded for almost four minutes.

"It took awhile for our power play to get going," Decker said. "Obviously we had a lot of chances throughout the night."

"If you look at all the units, they all can capitalize whenever. It's nice to have four lines that can be on the power play at any time. We use that depth to our advantage."

After a scoreless two periods and the U.S. carrying a 24-13 edge in shots, Fortino scored 14 seconds into the third for a temporary 1-0 Canadian lead.

Knowing how potent the Americans are when up a player, Canadian head coach Laura Schuler focused on special teams during last week's pre-tournament camp in Penticton, B.C.

"You can't ignore how good their power play is. I'm proud of our girls how they performed on the kill," Schuler said. "We've just got to find a way of putting the puck in the net more five-on-five and continue to work on building momentum we generated off our kill."

The U.S. have won six of the last eight world titles. They extended their winning streak against Canada to four in a row Monday. Canada's last victory against them was a 3-2 shootout victory in the 2014 Four Nations Cup final in Kamloops.