Martina Navratilova has slammed famous astrophysicist Neil deGrasse Tyson for his comments regarding the fluidity of gender identity.

Tyson's TikTok video on the topic went viral last month, in which the American gave his opinions on gender identity and expectations, expressing his belief that gender can be fluid.

"Suppose no matter my chromosomes, today I feel 80% female 20% female. I’m gonna put on makeup. I’m gonna do this. Tomorrow I might feel 80% female. I’ll remove the makeup and put on a muscle shirt," the 64-year-old said at the start of the video.

However, the 59-time Grand Slam champion disagreed with Tyson and took to social media to share her thoughts.

"Okay, I forced myself to watch this whole thing and all I can say is Neil Tyson is completely clueless while trying to sound knowledgeable and reasonable," she wrote on X, formerly known as Twitter.

The 66-year-old was responding to another critique of the comments by a social media user accusing Tyson of being part of a 'gender identity cult.'

Navratilova, who has been openly lesbian since 1981, is often seen criticizing transgender activism on social media. This led LGBTQIA+ group Athlete Ally to cut ties with her in 2019 as they felt she no longer aligned with their values after she accused transgender athletes of 'cheating' in a newspaper column.

"To put the argument at its most basic: a man can decide to be female, take hormones if required by whatever sporting organisation is concerned, win everything in sight and perhaps earn a small fortune, and then reverse his decision and go back to making babies if he so desires. It’s insane and it’s cheating," she wrote.

In response, the LGBTQIA+ athletic advocacy organization dropped her as a global ambassador and condemned her comments in a statement saying that Navratilova's words were based on false information and were transphobic.

"Navratilova’s recent comments are transphobic, based on a false data, and perpetuate dangerous myths that lead to the ongoing targeting of trans people. She has been removed from our Advisory Board and as an Athlete Ally Ambassador, effective immediately," they said.