"World No.1 Novak Djokovic has withdrawn from the 2022 ATP Cup. Team Serbia will now be led by world No.33 Dusan Lajovic," organisers said in a statement ahead of Saturday's start to the tournament.

There has been intense speculation as to whether 34-year-old Djokovic will travel to Australia, having refused to confirm if he has been inoculated against the coronavirus.

The nine-time Australian Open champion could win a record 21st Grand Slam title if he plays at Melbourne Park next month, but to enter Australia he and members of his entourage have to be vaccinated.

He has previously expressed his opposition to the vaccine and his father Srdjan said in late November that Djokovic would probably not play the first Grand Slam of the year, accusing the organisers of "blackmail".

Tennis Australia has organised charter flights to bring international stars into Melbourne and Sydney for warm-up tournaments.

Defending women's Australian Open champion Naomi Osaka was among those to touch down on Tuesday, but Djokovic was not on board. Players can also opt to fly commercial.

The Australian Open is due to start on January 17.