Djokovic withdraws from Australia's ATP Cup

The ATP Cup begins on January 1 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.
However, organisers have notified that Novak Djokovic has withdrawn from the ATP Cup in Australia ahead of the first Grand Slam tournament of the season. 
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.
Dusan Lajovic will replace Djokovic for Serbia. Fifth-ranked Andrey Rublev of Russia also pulled out, as did teammates Aslan Karatsev and Evgeny Donskoy.