The stars of the WTA marked Equal Pay Day in the U.S. by talking about their own views and experiences on the issue.

READ: Evolution of Prize Money - Fighting for equal pay

Caroline Wozniacki expressed her pride at being part of a sport where women and men receive equal prize money, saying, "Women are being heard. We're going in the right direction...You deserve to be equal with the men, gender really shouldn't matter."

"Being able to have equal pay in the Grand Slam and the Masters is very important," added Madison Keys, who also thanked those players who had fought for equality in the generations previously.

"It's improving year by year - I'm really glad that everyone has worked so hard," agreed Kiki Bertens.

"It's very important to set an example of how it should be," said Germany's Julia Goerges. 

And trailblazing Legend Billie Jean King urged more companies to commit to giving equal pay to men and women doing the same jobs.

The day was also marked by the US Open.