All 28 members of the United States women’s national team squad have begun legal action against the US Soccer Federation (USSF), just months before defending the Women’s World Cup title.
The discrimination lawsuit relates to equal pay and working conditions.
Players – including Carli Lloyd and Megan Rapinoe – are urging the governing body to “promote gender equality”.
It follows a discrimination complaint made by five American players in 2016.
The US have won the Women’s World Cup three times – at the inaugural 1991 tournament in China, the 1999 event hosted by the US and then in Canada four years ago.
The men’s team made the quarter-finals in 2002, while their best finish remains the third place in 1930.
The lawsuit, filed with the US District Court in Los Angeles, stated: “Despite the fact that these female and male players are called upon to perform the same job responsibilities on their teams and participate in international competitions for their single common employer, the USSF, the female players have been consistently paid less money than their male counterparts.