Novak Djokovic, the No. 1 men's tennis player in the world, has withdrawn from the ATP Cup in Sydney, Australia.
The ATP Tour announced Djokovic's withdrawal on Wednesday, as well as the withdrawal of world No. 5 Andrey Rublev. Dominic Thiem, who is still recovering from a wrist injury, pulled out earlier in the week.
The ATP didn't give a reason for Djokovic's withdrawal. He's not known to be suffering from any injuries. The Serbian team will still participate in the ATP Cup, which begins Jan. 1.
Djokovic's Australian Open status remains uncertain
Djokovic's withdrawal from the ATP Cup adds more uncertainty to his status for the Australian Open. Djokovic was on the entry list for the upcoming tournament, but questions remain about his ability to participate. While the ATP Cup hadn't established a vaccination mandate for its players, the Australian Open, which takes place in Melbourne, is requiring all its players to be vaccinated against COVID-19 in order to play in the tournament.
Djokovic has said in the past that he's "opposed to vaccination" and to vaccine mandates. He has repeatedly declined to reveal his vaccination status.
There is a chance Djokovic could still play at the Australian Open. The organizers will allow a small number of unvaccinated staff and players to participate if they're granted a medical exemption by an independent panel of experts. However, Djokovic's father recently said that his son won't defend his Aussie Open title due to the vaccine mandate.
Djokovic has 20 Grand Slam singles titles, tied with Rafael Nadal and Roger Federer for the most all time. If he decides to skip the Australian Open — as Nadal and Federer are — he'll have to wait for the French Open in May to attempt to set the record for men's Grand Slam singles titles. By that time, it's possible that Nadal or Federer could recover from their injuries and be ready to compete.