World number one Novak Djokovic has been entered into the Australian Open despite uncertainty over his Covid vaccination status, while seven-time winner Serena Williams is absent.
Defending champion Djokovic has refused to reveal if he has been vaccinated - a requirement to play in Melbourne.
Williams, 40, said she was not fit to compete at 2022's first Grand Slam.
"While this is never an easy decision to make, I am not where I need to be physically to compete," she said.
"I will miss seeing the fans, but am excited to return and compete at my highest level.