Lacasse and seven players on the U.S. national team are teammates on the Boston Blades of the Canadian Women's Hockey League.
Lacasse, from Kingston, Ont., will wear Canadian colours when she sees her American teammates at the Four Nations Cup starting Tuesday in Tikkurila and Kerava, Finland.
"We joke around about it," Lacasse says.
After the 23-year-old was named to Canada's Four Nations roster, she proudly tweeted a picture of her new pads adorned with the Maple Leaf.
Blades teammate and U.S. forward Kacey Bellamy's counter-tweet was: "I'm going to light you up tonight."
"They're giving me a hard time about my gear, but it's all in fun," Lacasse says.
The newest face among Canada's goaltenders is anxious to get in a Four Nations game, whether it's against the U.S., host Finland or Sweden.
Canada opens against the Finns on Tuesday before facing the U.S. on Wednesday and the Swedes on Friday. The championship game is Saturday. The Canadians downed Finland 8-1 in a warmup game Sunday with Charline Labonte in net for the visitors.
The U.S. is the defending Four Nations champion, beating the Canadians 4-3 in a shootout last year in Sweden.
Lacasse made Canada's world championship roster out of selection camp in April, but she didn't dress for any games while Canada won gold in Burlington, Vt.
Turnover among Canada's goalies is notoriously slow. There's only three goalie positions on the national team and there's also few game opportunities to move up the depth chart.
Edmonton's Shannon Szabados is Canada's starter for big games since her performance in the gold-medal game of the 2010 Winter Olympics in Vancouver. Labonte of Boisbriand, Que., has been a fixture on the roster for a decade.
A window opened for Lacasse on the senior team when Kim St. Pierre took last season off to have a baby boy.
St. Pierre has returned to her club team in Montreal, but indicated recently to a Montreal newspaper that a bid to play in the 2014 Winter Olympics is unlikely for her.
The 2013 world championships are in Ottawa in April. Canadian head coach Dan Church will likely name his world championship roster and the group of players who will try out for the 2014 Olympic team simultaneously next spring.
This week's Four Nations Cup provides a stage on which Lacasse can prove she belongs on both rosters.
"This is my chance to do it," she said.
She went early into an exhibition game against the U.S. last summer in Finland. Liz Knox was pulled after giving up two goals on the first two shots.
Lacasse made 45 saves on en route to Canada's 4-3 shootout win.
"She faced a lot of rubber and did really really well and kept us in the game," Church recalled. "We were able to eke out a victory in the end.
"She's a big-game player. Her technical skills are really starting to round into form. She's not just relying on her athleticism as a goaltender.
Lacasse finished both her marketing degree and college hockey career at Providence University this year. She returned to Rhode Island this fall to start a graduate degree in business and also take a job with the Friars as a goaltending coach.
With Boston a short drive away, playing for the CWHL's Blades was logical choice, even though the team consists of several players the Canadian wants to beat.
But having Hilary Knight, Meghan Duggan and Kelli Stack fire pucks on her regularly during Blades practices, as well as U.S. goaltender Molly Schaus pushing her for playing time, can help Lacasse in her bid to be an Olympian.
"It's a really good environment to be in," Lacasse said. "I know I can compete with those girls."
Canada's roster for the Four Nations includes almost all the players from the team that won gold at the 2012 world championship, minus defenders Laurianne Rougeau and Laura Fortino. Bobbi Jo Slusar of Swift Current, Sask., and Tara Watchorn of Newcastle, Ont., replaced them on blue-line for the Four Nations.
"We're starting to narrow in on a group of athletes we're going to consider for centralization," Church said. "The people who are omitted, it doesn't mean they won't be in that group at the end.
"All the players are still being evaluated."
The U.S., Finland and Sweden are also preparing their women's teams for the 2014 Games in Sochi, Russia.
The Finns have never beaten Canada in women's hockey, but goaltender Noora Raty has made Canada sweat in a few games lately.
"They're a team, based on their comments from people like Noora Raty, they believe they can beat us," Church said. "Another reason why this is important for us is to show them that they can't and to keep them from nipping at our heels."