Twenty-eight members of the United States women's national soccer team filed a lawsuit against the United States Soccer Federation on Friday for "institutionalized gender discrimination."

Andrew Das of the New York Times reported the legal filing, which includes USWNT superstars Carli Lloyd, Alex Morgan and Megan Rapinoe, is a sudden escalation of a long-term battle between the reigning world champions and U.S. Soccer over pay equity and overall treatment compared to the men's team.

The Americans will defend their FIFA Women's World Cup title in France in June after emerging victorious in the 2015 tournament.

In the lawsuit filed in Los Angeles' United States District Court, players are seeking back pay and damages for any female player who's represented the United States at the senior national level since Feb. 4, 2015, which could result in compensation amounting to millions of dollars if they win the case, per Das.

The New York Times report noted the players' allegations reflected many made in a 2016 complaint filed with the Equal Employment Opportunity Commission. Although the case was never resolved, the EEOC granted a right-to-sue letter to allow for a federal court filing.

After the 2016 filing, Morgan explained the players' stance during an appearance on NBC's Today, according to Mike Bianchi of the Orlando Sentinel.

"Every single day we sacrifice just as much as the men. We work just as much," she said. "We endure just as much physically and emotionally. Our fans really do appreciate us every day for that. We saw that with the high of [winning the World Cup in 2015]. We're really asking, and demanding now, that our federation, and our employer really, step up and appreciate us as well."

Although the sides reached a deal on a new five-year collective bargaining agreement in April 2017, the concerns about equal treatment have endured.

The lawsuit was filed on International Women's Day. The filing also comes three days after the USWNT secured a second-place finish in the 2019 SheBelieves Cup with a 1-0 victory over Brazil.