As the U.S. women's national team's defense has evolved over the past four years, so has Becky Sauerbrunn.

Normally quiet and studious, the center back who is about to embark on her third Women's World Cup has embraced her role as a veteran and has started to use her voice, both as a leader and as a mentor to the younger defenders.

"Obviously, she's a player with tremendous experience and just a player that really kind of embodies what it means to be part of this team. She's a great professional and very popular with her teammates because of how she contributes both on and off the field," coach Jill Ellis said. "She's a fierce competitor and one of the nicest people that you'll ever meet."

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Sauerbrunn anchors a back line that has changed significantly since the group won the World Cup in Canada four years ago.

That unit was stellar: The United States went 540 minutes without conceding a goal, the longest streak in the tournament since Germany's record 679 scoreless minutes from 2003-11.

Hope Solo allowed just three total goals and won her second straight Golden Glove for the tournament's top goalkeeper. The backline included Sauerbrunn, Meghan Klingenberg, Julie Johnston and Ali Krieger.

The faces alongside Sauerbrunn in France will change. Johnston, now going by her married name Ertz, has moved up into the midfield. Abby Dahlkemper, Crystal Dunn and Kelley O'Hara are expected to round out the starting four.

Solo is gone, dismissed from the team following the 2016 Olympics. Alyssa Naeher will likely start in goal during the tournament.

Sauerbrunn said the team's focus in recent years has shifted players toward the attack, prompting the defense to come up with new ways of doing things.

"In 2015, it wasn't just the backline. I think in general the whole team played a more defensive formation, and a defensive way of playing. We've changed that within the last four years and I think we're now a more attacking group," she said. "So when you're putting a lot of numbers forward in the attack, you just have to defend a different way. So it's very difficult to compare because we're playing two different styles of soccer."

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Sauerbrunn, 33, has been with the national team since 2008 and has 158 appearances with the team. In addition to playing on the 2011 and 2015 World Cup squads, she was part of the U.S. team that won the gold medal at the London Olympics. She also plays with the Utah Royals of the National Women's Soccer League.

On the national team, she is a mentor to the younger defenders, including Dahlkemper and Tierna Davidson, who was named last year's Young Player of the Year.

"I feel like I have taken on more of a vocal role. That comes with organizing the people around me; you obviously have to be very vocal. But also in a World Cup setting, you don't hear a lot, so you can't really speak beyond 15 yards to another person. And so it's really everyone's responsibility to kind of be looking around and aware where our players are, where their players are, because it comes down to it in some of those atmospheres you can't hear anything. But in those moments when you can say something, yes, I feel like that is a role that I have had to step into, and that I'm happy to step into."

She's also embraced a more vocal role off the field. She was among the five teammates — joining Solo, Alex Morgan, Carli Lloyd and Megan Rapinoe — who filed a complaint with the Equal Employment Opportunity Commission that accused the U.S. Soccer Federation of wage discrimination.

The players recently dropped the complaint to file a federal lawsuit against the federation, alleging "institutionalized gender discrimination" that includes pay inequitable to that of their counterparts on the men's national team.

"I feel that as I've gotten older, I've gotten more comfortable with myself and my opinions, and voicing those opinions. I always feel like I've been a good listener, and as I've gotten older I feel like I do partake more in discussions and in the fights that we, as a team, support. And I do think it's kind of an evolution for me. It mirrors the evolution of me as a player, but it's definitely the evolution of me as a person," she said.

Speaking to The Associated Press from the team's training camp in north London, Sauerbrunn said she wants to leave a legacy that will linger long after she's gone.

"If I had to think about what I would want to be known for, it's being a team-first player, I always wanted to do whatever it took to make the team better," she said. "And that goes for on and off the field."