Australian basketball player Liz Cambage has withdrawn from the Olympic team citing mental health concerns and fears of heading into the "bubble".
Cambage, who plays for the Las Vegas Aces, said the fact that family, friends and fans would not be in Tokyo to offer support was "terrifying".
The 29-year-old, a four-time WNBA All-Star, said she wanted to take care of herself "mentally and physically".
"At the moment I'm a long way from where I want and need to be," she said.
"It's no secret that in the past I've struggled with my mental health and recently I've been really worried about heading into a 'bubble' Olympics. No family. No friends. No fans. No support system outside of my team. It's honestly terrifying for me.
"The past month I have been having panic attacks, not sleeping and not eating.
"Relying on daily medication to control my anxiety is not the place I want to be right now - especially walking into competition on the world's biggest sporting stage."
Cambage's withdrawal comes amid reports she was involved in an incident during a warm-up game against Nigeria in Las Vegas, where the Australia team is holding a pre-Olympics training camp,
ESPN report she was involved in a physical altercation as well as a "charged verbal exchange".
It has also been reported she broke team protocols to go out in Vegas, in addition to another undisclosed incident.
Cambage, who won Olympic bronze at London 2012, had previously threatened to boycott the Games over a lack of racial diversity in Australia's Olympic photoshoots.
She accused the Australian Olympic Committee of "whitewashing" but later decided to compete at her third Games.