The 74-year-old Court, who won a record 24 grand slam titles in a glittering career, came under fire again on Wednesday when she claimed tennis was "full of lesbians" in a radio interview, a week after expressing her opposition to same-sex marriage.
"It is now clear exactly who Court is: an amazing tennis player, and a racist and a homophobe," Navratilova wrote in an open letter published by Fairfax Media.
"Her vitriol is not just an opinion. She is actively trying to keep LGBT people from getting equal rights (note to Court: we are human beings, too). She is demonising trans kids and trans adults everywhere.
"And now, linking LGBT to Nazis, communists, the devil? This is not OK. This is in fact sick and it is dangerous. Kids will suffer more because of this continuous bashing and stigmatising of our LGBT community."
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Czech-born American Navratilova said she had forgiven the Australian for calling her a bad role model in the 1990s "because I was a lesbian".
"Now she is doubling down with her ridiculous comments about older women luring young girls on the tour to parties to turn them into lesbians. It's a good thing she didn't name anyone as I am pretty sure she would be sued for defamation."
Court's views triggered speculation that some players might refuse to play in the Melbourne Park arena that bears her name at next year's Australian Open.
"The platform people like Margaret Court use needs to be made smaller, not bigger," Navratilova said, addressing the arena itself, while adding that another Australian great should be recognised instead.
"Which is why I think it's time to change your name. And I think the Evonne Goolagong Arena has a great ring to it. Now there is a person we can all celebrate. On every level."
(Reporting by Amlan Chakraborty in New Delhi; Editing by John O'Brien)
