The professional tennis tours and two other defendants jointly filed a motion in federal court in New York to dismiss the class-action antitrust lawsuit filed by the Professional Tennis Players’ Association, a group co-founded by Novak Djokovic.

The PTPA sued the WTA women’s tour, the ATP men’s tour, the International Tennis Federation (ITF) and the International Tennis Integrity Agency (ITIA), which oversees anti-doping and anti-corruption efforts in the sport, in March, calling them a “cartel.”

The players are seeking a greater share of revenues and also raised various other complaints about how tennis is structured, including limits on prize money and a lack of competition from rival tours or tournaments.

The PTPA was founded by 24-time Grand Slam champion Djokovic and Vasek Pospisil with the aim of representing players who are independent contractors in a largely individual sport.

The group’s executive director, Ahmad Nassar, repeatedly has said it is not a full-fledged union, does not have members and does not collect dues — all of which are pointed to in one of Tuesday’s motions as reasons why the PTPA does not have standing as a plaintiff in the case. That motion came from all four defendants.

A separate motion, filed only by the WTA, says that the male plaintiffs — 2022 Wimbledon runner-up Nick Kyrgios, Reilly Opelka and Tennys Sandgren were among those named — should not be suing the women’s tour, and also argues that the female plaintiffs — who include Sorana Cirstea and Varvara Gracheva — should be compelled to go to binding arbitration instead of pursuing the court case.

“There is nothing surprising in their motions,” the PTPA said in a statement to The Associated Press. “We’ve researched all the issues at length, before filing our case, and look forward to responding in due course and having the judge decide.”