Roger Federer has been called out by fellow tennis legend Billie Jean King for not offering more support to the equal prize money campaign in the sport. King is considered a trailblazer, not only in women’s tennis but sport in general, having campaigned for gender equality, equal pay, and LGBTQ+ rights.

The American became the first female athlete to break the $100,000 (£74,000) barrier for career earnings back in the 1970s, and King finished her playing career with a whopping 39 Grand Slam titles across all formats. She is synonymous with tennis in the same way that Federer is, but the two appear to be at loggerheads.

That’s because in an interview with Racquet, King criticised Federer for not being a bigger proponent of the equal prize money movement. She remarked: “I wish he would fight for equality more because I keep saying, ‘You have two boys and two girls! You have equality in your household!”

King made it clear she doesn’t think Federer is inherently against it, rather she’d prefer to see him do more to stick up for it, saying: “You think he’d ever do anything to rock the boat? He doesn’t want to. I’d want to make money, too.”

Federer’s last comments on equal prize money came back in 2016 during the Miami Open, when the Swiss star offered somewhat of a neutral answer. He said: “I’m all for equal prize money.

“But then you have to look at the history of each and every event, where it came from. Some tournaments were a men’s tournament, then the women joined or vice versa, it was a women’s tournament and we joined them. It’s sometimes hard to make equal prize money there. It’s up to the tournament director to decide if he wants it to be that way.”

He added: “When I was fighting for prize money increases, especially at the Slam level. I was always very aware of the fact that it was always going to impact the women’s game, which I was very happy about. Both at the same time were growing.

“I mean, we don’t always get the same like the women, as well. I think it depends on what tournaments we are talking about. I think you have to be very specific what you’re talking about.”

Ever since 2007, all four Grand Slams have been committed to equal prize money in the men’s and women’s singles events. However, there still remain disparities in men’s and women’s events at lower-tier tournaments, with organisers having set out timetables to try and bridge the gap.