Novak Djokovic has withdrawn from the ATP Cup in Australia ahead of the first Grand Slam tournament of the season, organizers said Wednesday.
No reason was given but the top-ranked Serb has declined to comment on his vaccination status in recent months and Australia's strict regulations require all players, officials and fans to be fully vaccinated against COVID-19.
ATP Cup organizers disclosed Djokovic's withdrawal in a roster update that included France replacing Austria in the 16-country event following the withdrawals of Dominic Thiem and Dennis Novak. Dusan Lajovic will replace Djokovic for Serbia.
Fifth-ranked Andrey Rublev of Russia also pulled out, as did teammates Aslan Karatsev and Evgeny Donskoy. The ATP Cup begins Saturday in Sydney.
The Australian Open men's entry list announced in early December had the 34-year-old Djokovic at No. 1 in what was seen as a further indication that he'll be playing at Melbourne Park beginning Jan. 17 despite Australia's tight regulations.
The nine-time Australian Open champion is tied with Roger Federer and Rafael Nadal for the men's record of 20 Grand Slam singles titles.