After a boisterous rendition of “O Canada” under the towering, imperial gates near Toronto Stadium, Stephen Hills soaked in the moment beneath a perfect sun and blue sky, wearing a red and white flag like a cape.

Soccer loyalties tend to run along bloodlines, so Mr. Hills, of Wasaga Beach in southern Ontario, had been a longtime supporter of England because of his family’s heritage. But in the years since Canada scored the country’s first World Cup goal in Qatar in 2022, his devotion has shifted.

“This just seems like a turning point for Canadian soccer,” Mr. Hills said.

And, too, for Canada.

The country has been in the midst of a minor identity crisis. On the global stage, it has dutifully played the role of the peacekeeper, the soft power, and friend and partner of other middle-power nations, as President Trump has harmed the Canadian economy with tariffs and repeatedly threatened to make Canada the 51st state.

Canadians have thrown their elbows up, assuming a defensive posture that may have initially felt unnatural. But Canada is now co-hosting the World Cup with Mexico and the United States, and on Friday afternoon it welcomed the colors and flags of the world.

Canada’s men’s national team, which played Bosnia and Herzegovina in its first game, had never won a match at its previous World Cup showings in 2022 and 1986, but the team could make the knockout stage this year, fueling excitement around the three games it will play in Toronto and Vancouver in the group stage.

Cam Parra, whose bar, the Brazen Head Irish Pub, is a 10-minute walk from the stadium and a regular haunt for soccer fans, opened his doors at breakfast time on Friday. There’s a television in virtually every corner.

“To see the sport that we love, the sport that our guests love, being hosted in the city that we love as well,” Mr. Parra said. “It feels unreal.”

Hours before kickoff, throngs of fans filed into the stadium, belting versions of “Go on, you boys in red!” and the “Olé, olé!” chant. Police officers reluctantly took photos of Canada supporters who approached them with cellphone cameras. Gift shops, food trucks and fan zones were sprinkled along the lakefront route to the stadium.

The mood was electric, but for all the activity, there was still a fair bit of breathing room. And that was partly because many fans were priced out of tickets, which ran around 1,000 Canadian dollars on the low end (about $715), and left hundreds of tickets still available the day before the game. Torontonians also braced for huge crowds and delays driving and taking public transit and in getting access to the stadium.

The stadium in Toronto is the smallest being used in the FIFA tournament, seating about 45,000 people, and that is after a monthslong retrofit that added 17,000 temporary seats, mounted with metal scaffolding. Canada is hosting 13 matches, six in Toronto and seven in Vancouver.

Even in the birthplace of ice hockey, soccer is the country’s most-played sport, according to a recent national survey. One of the most prolific training grounds for the country’s young soccer stars is Brampton, Ontario, a suburban city west of Toronto that is home to a number of players on Canada’s roster.

The team’s captain, Alphonso Davies, 25, was born in a refugee camp in Ghana, where his family had fled during a period of civil war in Liberia, and immigrated to Canada a few years later. (Mr. Davies is out for the first game with a hamstring injury.)

His story, of escaping war and finding refuge in Canada, is a common theme among Canada’s opponents, Bosnia and Herzegovina. Canada resettled 5,000 Bosnian refugees in 1992, most of them Muslims who were fleeing ethnic cleansing campaigns at the start of the Bosnian war, one of the many conflicts from the Yugoslav war that bled into the early 2000s.

Just outside the ticketing gates, Lejla Karamesic knelt down so a face-painter could adorn her cheek with the yellow and blue Bosnian flag as her husband, wearing a Canada jersey, looked on.

“Whichever country wins, I think we’ll both be super stoked,” said Ms. Karamesic, who was born in Sarajevo and immigrated with her family in 1996, and had plans later that evening to watch the Toronto Blue Jays against the New York Yankees at the Rogers Centre.

“Today I’m just going to die of exhaustion,” said Ms. Karamesic, “but it’ll be the best sports day ever.”