Moore, who has already walked back from his comments, over the weekend was asked about his thoughts on the Women’s Tennis Association. He said that he felt the WTA players “ride on coattails of the men. They don’t make any decisions and they are lucky. They are very, very lucky.” He went on to add that female players should go down on their knees to thank male stars like Roger Federer for carrying the sport.

Those comments drew quick responses from Williams and Djokovic, who essentially argued different points of the debate about pay in the world of tennis. Williams called Moore’s statements “mistaken and very, very, very inaccurate,” saying she and her sister Venus Williams–as well as many other female professional athletes–brought fans to the sport.

Djokovic, meanwhile, said that while he thought women should get admiration and respect for what they do on the court, he believed that there was data that supported the notion that men bring in more fans to their matches. He added women deserve respect because they have “hormones.”

This debate essentially brings up the issue of equal pay, which has been a controversial subject in the tennis world for many years. Women now earn equal prize money at all four major tennis tournaments but two of them–Wimbledon and Roland Garros–only made the change in the past decade. Tennis legend Billie Jean King led the charge for equal pay for female tennis players, though Venus Williams has also been a notable advocate for the cause.

Other lower tournaments have also agreed to equal payouts. At Indian Wells’ BNP Paribas Open, the pay is a little over $1 million to the winner, regardless of gender. Djokovic defeated Milos Raonic this year, while Williams lost in the final to Victoria Azarenka. As a finalist, Williams earned $501,815.