Minnesota United captain Francisco Calvo remembers playing soccer as a young kid in the streets of his native Costa Rica, sometimes even without shoes, let alone the expensive boots he wears as a professional now.

"We are only 5 million people over there, and football, it's everything in Costa Rica," Calvo said.

The 25-year-old's passion for the game has led the defender to the realization of a lifelong dream, as he will represent his country starting Sunday in the 2018 FIFA World Cup in Russia.

Costa Rica will open its World Cup campaign 7 a.m. Sunday against Serbia before playing Brazil at 7 a.m. Friday and Switzerland at 1 p.m. June 27. The team, which also features on-loan United midfielder Johan Venegas, will need to finish as one of the top two squads in that group to advance to the knockout rounds.

But making that is a long shot for Costa Rica.

"That's why I'm confident they'll be back here before the end of the first phase," United coach Adrian Heath joked of Costa Rica's chances. "They've got a tough group."

Calvo acknowledged Costa Rica has a difficult road ahead, but he's also pretty confident in his national team.

"We are really a strong group, and we know that when we play together, we demonstrated last World Cup we can do a lot of good things," Calvo said of 2014's tournament, when Costa Rica won its group and lost in the quarterfinals on penalty kicks. "I can't say we're going to do better or the same because we don't know. … But we're going to try to do our best. If we can at least try to do the same, it would be awesome."

While he's an undeniable starter at center back for the Loons, Calvo will be fighting for a starting spot mainly at left back for Costa Rica in his first World Cup. Even though he remembers watching his country play in the 2002 World Cup when he was about 10, he's not concerned about the moment overwhelming him.

"It's part of your job," he said. "You're going to be in the world stage, so everybody's looking at you. Everybody's looking at your country. We are a small country, and we need to take these opportunities. And for me, I want to keep doing my job to try to improve every game, try to improve my football, try to improve my career and just come back here and do the best for Minnesota."

Heath said he wouldn't be surprised if Calvo had a great tournament and used it as a springboard for his career. But that would also do some good for the club's brand, as people from all across the world have the chance to hear about United because of Calvo.

Even during the biggest opportunity of his career, Calvo said he'll still be worrying about the Loons, who will go on playing without him. But he's also engrossed making his country proud, including those little kids playing on the street like he once was.

"We know we represent the country," Calvo said. "When the national team wins, the country's happy. When we lose, the country's not happy. You can't imagine how it was in Brazil when the guys come back from the World Cup, the president gave two or three days free because that doesn't happen a lot. So I hope we can do the same thing."