Martina Navratilova has claimed fellow tennis legend and Wimbledon pundit John McEnroe is paid at least 10 times more than her by the BBC.
The 61-year-old revealed she receives around £15,000 for being a commentator for the broadcaster during the Grand Slam tournament in London.
McEnroe's pay packet, of £150,000 to £199,999, was revealed in a list of the BBC's top-paid talent last summer.
Navratilova, who won 18 Grand Slam singles titles in a career spanning three decades, said she was told she was getting paid a comparable amount to men doing the same job as her.
The tennis star said she would be asking for more money in the future.
"It was a shock because John McEnroe makes at least £150,000," she said.
"I get about £15,000 for Wimbledon and unless John McEnroe's doing a whole bunch of stuff outside of Wimbledon he's getting at least 10 times as much money."
She continued: "We were not told the truth, that's for sure….
"(I'm) not happy… It's shocking… It's still the good old boys network…. The bottom line is that male voices are valued more than women's voices."
Navratilova made the revelations to Panorama, the BBC's investigative documentary programme, in an episode to be aired later this evening.
BBC Sport told Panorama that "John and Martina perform different roles in the team, and John's role is of a different scale, scope and time commitment".
It said that "along with Sue Barker", McEnroe – who retired with seven career Grand Slam singles titles to his name – "is regarded as the face of our Wimbledon coverage".
"He is a defining voice within the BBC's coverage," it said.
"He is widely considered to be the best expert/commentator in the sport, highly valued by our audiences and his contract means he cannot work for another UK broadcaster without our permission."
It said their roles were "simply not comparable", adding: "His pay reflects all of this; gender isn't a factor."
The dispute adds to an ongoing and broader gender pay row at the publicly-funded broadcaster after the disclosure of the salaries of its biggest stars.
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Figures published in 2017 revealed just two of the top 10 earners were women, and examples of huge disparities between the salaries of male and female actors and presenters, with the men earning more for doing similar jobs with similar experience.
Radio 2's Chris Evans topped the list on more than £2m, while the highest paid woman was Claudia Winkleman on between £450,000 and £499,999.