Serena Williams believes it's "OK not to be OK".

The 42-year-old former sports star has taken to social media to admit that she's "not OK" - but she's also insisted that it's not a problem, either.

Serena - who is widely regarded as one of the greatest tennis players of all time - wrote on X: "I am not ok today. And that’s ok to not be ok. No one is ok every single day. If you are not ok today I’m with you. There’s always tomorrow [kiss emoji] Love you. (sic)"

Serena announced her retirement from tennis in 2022.

However, she previously confessed that retirement was a "taboo topic" in her house before she quit the sport.

She told Vogue magazine: "I’ve been reluctant to admit to myself or anyone else that I have to move on from playing tennis.

"Alexis, my husband, and I have hardly talked about it; it’s like a taboo topic. I can’t even have this conversation with my mom and dad. It’s like it’s not real until you say it out loud.

"It comes up, I get an uncomfortable lump in my throat, and I start to cry. The only person I’ve really gone there with is my therapist! One thing I’m not going to do is sugarcoat this."

Serena admitted that, unlike some of her rivals, she never really wanted to retire.

She said: "I know that a lot of people are excited about and look forward to retiring, and I really wish I felt that way.

"Ashleigh Barty was number one in the world when she left the sport this March, and I believe she really felt ready to move on. Caroline Wozniacki, who is one of my best friends, felt a sense of relief when she retired in 2020."