The latest chapter in the labor battle between the U.S. women's national team and U.S. Soccer involves five prominent players and a filing to the Equal Employment Opportunity Commission.

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In the latest labor salvo between the World Cup-winning U.S. women’s national team players and the U.S. Soccer Federation, the five most prominent members of the USWNT have filed an action with the Equal Employment Opportunity Commission (a government agency) accusing U.S. Soccer of wage discrimination in relation to the money the federation pays to the U.S. men’s national team.

In a press release announced Thursday morning, lawyers for the five U.S. players—Carli Lloyd, Alex Morgan, Hope Solo, Megan Rapinoe and Becky Sauerbrunn—argue that the USWNT is paid almost four times less than the USMNT, despite producing nearly $20 million in revenues for U.S. Soccer in 2015 (per U.S. Soccer’s recently released annual financial report).

The U.S. Soccer pay figures for the men and women (numbers from documents obtained by SI.com are presented in the table below) were agreed to by the players as part of separate collective bargaining agreements, but the U.S. women’s team argues that its CBA has expired.

Payment situation USWNT

(2013-present) USMNT

(2015-18) Friendlies (per player, vs. teams not in FIFA's top 25, excluding Mexico) $1,350 for a win $9,375 for a win;

$6,250 for a tie;

$5,000 for a loss Friendlies (per player, vs. teams ranked 11-25, excluding Mexico) $1,350 for a win $12,500 for a win;

$6,250 for a tie;

$5,000 for a loss Friendlies (per player, vs. teams ranked 1-10 and Mexico) $1,350 for a win $17,625 for a win;

$8,125 for a tie;

$5,000 for a loss World Cup roster bonus $15,000 per player WCQ match bonus;

$15,000 per player WC roster bonus $68,750 per player World Cup qualifiers N/A $12,500 per player per win; $6,000 per player per draw; $4,000 per player per loss World Cup qualification N/A $2,500,000 split among team player pool World Cup per game payment N/A $6,875 per player, regardless of result World Cup first round points bonus N/A $218,750 to team player pool per point earned World Cup second round advancement bonus N/A $4,500,000 split among team player pool World Cup fourth place bonus $10,000/player N/A World Cup third place bonus $20,000/player $1,250,000 to team player pool World Cup second place bonus $32,500/player $6,250,000 to team player pool World Cup champion bonus $75,000/player $9,375,000 to team player pool Player in World Cup training camp, not game roster N/A $2,500 Per Diem $50/domestic venue; $60/international $62.50 domestic;

$75 international Sponsor appearance fee $3,000/appearance $3,750/appearance Attendance ticket revenue bonus $1.20/ticket $1.50/ticket Post-World Cup victory tour (number of games dependent on WC outcome; tour dependent on WC finish) $1.8M for team player pool for finishing first in World Cup;

$6,750 per player for finishing second;

$6,250 per player for finishing third N/A

U.S. Soccer, for its part, has maintained that the CBA with the U.S. women’s players is still in effect through the end of 2016 due to a memorandum of understanding signed by the two sides in 2013. In an effort to get a court to decide if the CBA is still in place, U.S. Soccer filed its own separate action in February in Chicago. Discovery for that case was set to be completed on Thursday, with oral arguments on the motions set to take place before the Chicago court on May 25.

The USWNT players are being represented by Jeffrey Kessler, one of the nation’s most prominent sports lawyers, who represented Tom Brady in his recent case against the NFL. Kessler told SI.com that the new players action had nothing to do with the Chicago case filed by U.S. Soccer.

“The reason the players have filed is because the USSF has made it clear that they will not consider equal pay [with the U.S. men] in the negotiations for a new agreement,” said Kessler. “So whether or not there’s an existing agreement, they won’t ever agree to make a change to give us the right salary. And the players have been very patient and have concluded now they have to bring a case.”

U.S. Soccer responded Thursday morning with the following statement: "We understand the Women’s National Team Players Association is filing a charge with the Equal Employment Opportunity Commission against U.S. Soccer. While we have not seen this complaint and can’t comment on the specifics of it, we are disappointed about this action. We have been a world leader in women’s soccer and are proud of the commitment we have made to building the women’s game in the United States over the past 30 years."

The federation then added the following:

One topic at issue is whether the U.S. women could initiate a work stoppage before the Olympics in August, which would give them much more leverage in negotiations for a new CBA.

“I’m not going to make any comment about those issues right now,” Kessler said.

In the press release, Kessler notes that the U.S. women’s players want “equal pay for equal work,” while Morgan adds that the team wants treatment equal to the U.S. men on playing surfaces and travel accommodations.

The U.S. players say their goal is for the EEOC to conduct an independent investigation, issue its findings and seek relief on behalf of the players on the U.S. team.

“These athletes have probably the strongest case for pay discrimination against women that I have ever seen,” Kessler argued. “Because you have a situation where not only are their work requirements identical to the men’s requirements—the same number of minimum friendlies they have to play, the same requirements to prepare for their World Cups—but they have outperformed the men both economically and on the playing field in every possible way the last two years. So this isn’t a case where someone can come in and say the reason the men are paid more is because they are more economically successful or the men outperform the women or they’re not comparable in the same way.”

The U.S. women’s team is currently in camp ahead of friendlies on April 6 and 10 against Colombia. The Olympic women’s soccer tournament is set to begin on August 3.