Tennis legends Venus and Serena Williams have teamed up with tennis great Billie Jean King to fight for equal pay in every field, the Associated Press reports.

Venus Williams famously fought for equal pay for men and women at Wimbledon in 2005. She was successful, and her win there moved the French Open to offer equal pay for all of its competitors as well.

“I said: ‘All of our hearts beat the same. When your eyes are closed, you really can’t tell, next to you, who’s a man and who’s a woman.’ And [I asked them] to think about their daughters and their wives and sisters. How would they like them to be treated?” Williams recalled. “Sometimes, we lose track of, and don’t even realize, our own bias and our own prejudice. And we have to confront ourselves.”

During her time on the court, King pushed the U.S. Open to pay its athletes equally, and also ensured that professional tennis players were properly compensated. After retiring, she began fighting inequality through the Billie Jean King Leadership Initiative, the organization the Williams sisters have now joined as advisory board members.

“Venus, in particular, helped us get equal prize money in the majors," King said. "She was amazing. She really got Wimbledon to make the big step. Venus has always had the courage to step up. And Serena’s the same way. They step up. I mean, Serena is not afraid to say whatever is on her mind.”

King continued, “They’ve been through a lot themselves, so they totally understand what’s going on. The two of them have transcended sports. The BJKLI is not about sports. It’s about every industry. To try to get equal pay for equal work, and that means across the board, from CEOs down to entry level.”

The Williams sisters served the love right back at King, saluting the legacy she is creating. 

“We always put our hands up for Billie," Venus Williams said. "We love her. She has a tremendous history, not just in women’s tennis, but in leading rights for people, in general, no matter who they were. Billie could be at the point in her life now where she could say, ‘Hey, I’m going to sit back and enjoy my life.’ But she’s still working hard for others. And that’s a prime example for every single person. Your work on this earth never ends, as long as there is inequality.”

The announcement coincides with Equal Pay Day, the day that marks the point at which a woman's pay matches what a man made in the past year. 

King said that while she has no plans to stop fighting the good fight, she is please she has found young allies.

“I am in my 70s, so I am looking to younger people to take up the mill as I phase out over time,” King said. “I’ve got energy right now, so we’re teeing everything up so we’re in great shape for the legacy of the BJKLI, because I want it to have a life after I’m out of here.”