World number one Novak Djokovic was named on the official entry list for next year's Australian Open on Wednesday but 23-times Grand Slam singles champion Serena Williams will not play on the advice of her medical team.
Djokovic has declined to disclose his vaccination status despite all players, officials, staff and fans at the January 17-30 tournament at Melbourne Park needing to be inoculated against COVID-19.
Tennis Australia later told local media that his presence on the list was not a guarantee the Serbian would play.
Williams, who won the last of her seven Australian Open titles in 2017, had an injury-disrupted season and has not played since she limped out of her first-round match at Wimbledon in June due to the leg injury.
Tournament organiser Craig Tiley said last month that the 40-year-old American, who needs one more Grand Slam title to match Margaret Court's record of 24, would be playing at Melbourne Park.
"Following the advice of my medical team, I have decided to withdraw from this year's Australian Open," Williams said in a statement.
"While this is never an easy decision to make, I am not where I need to be physically to compete. I will miss seeing the fans but am excited to return and compete at my highest level."
Djokovic, who will be bidding for a record 21st Grand Slam men's singles title if he plays at the tournament, said last week that he would be making a decision "very soon" about travelling to Australia.
The 34-year-old was also named in the Serbia team for the ATP Cup, which will be held in Sydney in early January, when that was released on Tuesday.
Williams' name was the most obvious omission from the field with 20-times Grand Slam champion Roger Federer having already confirmed that he would skip the event as he recovers from another round of knee surgeries.
Stan Wawrinka, who won the first of his three Grand Slam titles at Melbourne Park in 2014, was also absent from the men's field.