When Lynn Klas was a kid, hardly a day went by when her feet didn't roll across the Wisconsin earth. Whether she was teaching her friends to skate or honing her own skills, Klas was so enamored of the roller-skating scene that she took a job working at a snack bar at a nearby rink when she was a teen.

Today, the woman known as "Juke Boxx" is hot-dogging it all over the globe.

Klas, who was introduced to roller derby seven years ago, has competed from coast to coast, played for Team USA in a World Cup, and even coached derby players from Spain to the South Pacific. Last winter, she left her longtime team, the Minnesota RollerGirls, to move to London and get married. She also followed her heart to a new team.

This weekend she's back in the United States, going for the Hydra Trophy at the Women's Flat Track Derby Association International Championships in Nashville, Tennessee, as a member of the London Rollergirls. The tournament opens Friday and the champion will be crowned Sunday.

And Klas, one of a handful of elite players who has crossed not just state borders but continents to play with a top team, likes her chances.

Bonnie Thunders, left, and Gotham could collide with Stefanie Mainey and London this weekend at the WFTDA championships. Shirlaine Forrest/Getty Images

"I think there's been a shift," the 28-year-old Klas said, "and ... international teams are the ones bringing the most change to the sport."

In the past, she said, "stateside teams taught everyone the best ways to play. But I think this year there's a whole re-imagination of what defense looks like, what offense looks like, and what timing looks like in roller derby."

After settling abroad, Klas signed on with London Brawling, London's all-star travel team, and joined prolific players such as jammer Jessica "Rogue Runner" McCarroll and Team England captain Stefanie Mainey.

While playing for Minnesota, Klas made Team USA in 2011 as one of its youngest members and played in the sport's inaugural World Cup in Canada. Despite her own success in roller derby, she's humbled to play with such a talented team in England.

"At London, I don't really stand out maybe in the way that I did on my other teams," said Klas, who plays both offense and defense. "That's probably a good thing."

Last November marked the London Rollergirls' first trip to the WFTDA championships, and they became the tournament's first team from outside the United States. This year's tournament features 16 teams from five countries -- the United States, Canada, Germany, Australia and Great Britain. As a testament to London's talent, the team secured a first-round bye after beating the Windy City Rollers in a regional playoff in September. London could potentially play Klas' former team, the Minnesota RollerGirls, on Saturday afternoon.

Roller derby has grown quickly in recent years, sprouting upstart leagues and national teams from Portugal to Peru, Switzerland to South Korea. Some think the game's growth is natural, while others contend that YouTube and social media have heightened the sport's visibility. Klas talks up another catalyst.

"The World Cup was a huge, huge factor in motivating people," Klas said. "It gave players outside the U.S. something tangible, to [want to] join WFTDA and get experience competing in the States." The second installment of the World Cup is scheduled for December, and 30 teams from six continents -- North America, Africa, Europe, Asia, Australia and South America -- will descend upon Dallas.

Karolina Berglöf, who skates as "Swede Hurt," played for Sweden in the 2011 World Cup. The blocker, who also won her country's MVP award, traversed the Atlantic this summer specifically to rejoin her old team, reigning WFTDA champion Gotham of New York City. She thinks Europeans' stance on sports may have spurred roller derby's quick surge abroad.

"In Scandinavia people are athletic. Everyone does sports for fun, even if not playing competitive," said Berglöf, who is on sabbatical from her job in investment management while she skates with Gotham. "Pretty much everyone I grew up with knew how to ice-skate. So teaching people how to roller-skate [for derby] is not as hard as in other countries."

After playing with three different teams in the United States, Berglöf, a former competitive snowboarder, went back to Sweden in 2011 to help upstart roller derby leagues in Malmö and later in Stockholm. Just three years ago, derby was very new in Sweden.

Berglöf called on her resources, such as Gotham teammate and derby legend Bonnie Thunders, for insight on how to train new players. About the same time, in April 2011, Klas started coaching roller derby clinics in Sweden before moving on to fill the demand in places such as Germany, Mexico, Finland and Australia.

Neither of Berglöf's former teams from Sweden has made it to the championships yet, but three other international teams join the London Rollergirls this year. Bear City of Berlin makes its debut along with Australia's Victorian Roller Derby and Canadian outfit Rideau Valley. Still, Gotham is the favorite.

"I can work my whole life, but can't play derby forever," Berglöf said. "Gotham is a team I really admire and want to be a part of -- especially in the championships -- right now."