RIO DE JANEIRO - Lori Chalupny was called one of the "top five players in the world" a few years ago by a former coach.

Last year her current club coach Rory Dames at the Chicago Red Stars described her as "a top-five player" in the National Women's Soccer League.

Yet, despite playing for professional club teams, Chalupny hasn't played for the United States national team in five years, sidelined by a history of concussions that left officials uncomfortable about selecting her.

That changes this week in Brazil, where Chalupny has returned to the U.S. squad for a four-team tournament, starting Wednesday, in the capital Brasilia against Brazil, China and Argentina. She's hoping to make the final American team for next year's World Cup in Canada.

"She (Chalupny) went to U.S. Soccer and went through a very extensive process — went through a medical screening — and she got cleared," U.S. Coach Jill Ellis said in an interview in Brazil with The Associated Press. "She was one of the best players in the NWSL the last few seasons, and if she was available for selection I was going to bring her."

Concussions have become an issue in soccer. High-profile incidents of injured player staying on the field in this year's men's World Cup in Brazil prompted FIFA — soccer's world governing body — to give referees powers to halt play while head injuries are assessed.

Chalupny, who figured she had little chance to return, said she contacted U.S. Soccer earlier this year about another chance. She was asked to undergo two independent examinations, and U.S. Soccer's chief medical officer George Chiampas eventually cleared her return.

"I'm beyond excited for this opportunity," Chalupny said on a conference call. "When everything happened, a couple of years ago, I understood U.S. Soccer's position. ... Hearing the news was not easy to take, but I definitely understand U.S. Soccer's position. That being said, I feel great."

Head injuries were again the focus last year when American striker Abby Wambach, probably the Americans' most famous player, was allowed to continue playing in a club match despite a clear concussion. Studies seem to show that female soccer players sustain more concussions than male players.

"I definitely would not be playing, and I wouldn't have been playing these last five years, if I felt that I was at potential risk," Chalupny said.

Chalupny has 92 caps for the U.S., eight goals and won a gold medal in the 2008 Olympics in Beijing. She was also in the third-place team at the 2007 World Cup in China. She hasn't played a match for the United States since 2009.

She can play anywhere — forward, midfield or defence — and as a left-footed player, she is a natural to fill the spot at left back.

"I saw her in the 2008 Olympics and I thought she was the best left back in the world, absolutely," Ellis said. "She hasn't played at this level for a long time and there is an adjustment, but based on her level of play in the league, she'll be able to impact this roster."

The No. 1-ranked Americans have a training camp in January, followed by friendlies in Europe prior to the Algarve Cup in Portugal. A team official said the World Cup team would probably be named about a month before the World Cup opens June 6.

Ellis said several players have been rotating at left-back and competition will be tough. She said Chalupny had not played in three months and lacked match fitness.

"I'm not sure how many minutes — if any — she (Chalupny) will get in this tournament," Ellis said. "We have new players, veterans. The reality is they are all competing for spots."

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Stephen Wade on Twitter: http://twitter.com/StephenWadeAP