Serena Williams suffers from regular migraines.
The 38-year-old tennis star has confessed she has battled periodic migraine attacks since she was in her 20s, and learned to "play through the pain" in her head because she didn't think it was an excuse to "stop playing" tennis.
Serena - who was coached by her dad Richard until 2012 - said: "Migraine isn't a knee injury - it's something you can't physically see. You can't really say, 'Oh, Dad, I have a migraine. I'm going to stop playing.' People are like, 'I don't see swelling. I don't see bruising. Tough it out.' I got used to playing through the pain."
The sporting superstar says there have been "so many" matches where she just had to power through her migraine attacks.
She added: "You can't go into a press conference with the media asking, 'Well, what happened?' and say 'Well I had a migraine attack.' I had to figure out a way to work through it."
Serena's migraines are made worse by stress, and amid the uncertainty of the coronavirus pandemic, she has been suffering with pain almost every day.
She explained to People magazine: "It's all incredibly stressful. I was dealing with a lot of stress and unknown factors and things that I wasn't used to, and so I think that was contributing to my migraine attacks and making them more frequent."
The beauty also had to keep up with her two-year-old daughter Olympia - whom she has with her husband Alexis Ohanian - and admits her migraines have been keeping her up at night.
To help ease her pain, Serena's doctor prescribed Ubrelvy - which is a drug designed to pain and symptoms during a migraine attack - and the star found it worked so well that she's now signed on as a spokeswoman for the product.