This file photo taken on Jan 27, 2019 shows Serbia's Novak Djokovic reacting after a point against Spain's Rafael Nadal during the men's singles final on day 14 of the Australian Open tennis tournament in Melbourne. (SAEED KHAN / AFP)

MELBOURNE - With players starting to arrive in Sydney for the men's season-opening ATP Cup, there was still no clarity on Monday whether top-ranked Novak Djokovic would be taking part in the team tournament or in the Australian Open that follows.

There has been intense speculation over Djokovic's participation at the Australian Open, which starts on Jan 17, with the 34-year-old, who is opposed to vaccinations, repeatedly declining to say if he has been innoculated against COVID-19. The rate of vaccination in the top 100 in men's tennis is 95 percent, according to ATP Tour data.

The rate of vaccination in the top 100 in men's tennis is 95 percent, according to ATP Tour data

With the organizers of the Grand Slam confirming that all players and participants at Melbourne Park must be vaccinated or have a medical exemption granted by an independent panel of experts, Djokovic has kept everyone guessing.

If the Serbian does not turn up, world No 2 Daniil Medvedev would be the top draw at the ATP Cup, and he has already arrived in Sydney to help Russia defend its title.

Djokovic, 34, has won a record nine Australian Open titles, including the last three, and the chances of him playing Down Under improved when he was named in Serbia's team for the ATP Cup.

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But on Saturday, a report in Serbian daily Blic said Djokovic would not be travelling to Sydney for the tournament, adding to doubts over whether he will play at Melbourne Park from Jan 17.

In this file photo taken on Nov 26, 2021, Serbia's Novak Djokovic hits a backhand against Austria's Dennis Novak during a Davis Cup group F match between Serbia and Austria in Innsbruck, Austria. (MICHAEL PROBST / AP)

His father Srdjan told a Serbian television channel last month that Djokovic would probably pull out of the major, saying Tennis Australia's stance on mandatory vaccination was tantamount to "blackmail".

Djokovic's pullout will, however, not impact Serbia's participation in the tournament which has a $10 million prize purse, with the teams locked in on Dec 7 based on player entries.

Owing to Djokovic's current world ranking, Serbia received top billing for the 16-team ATP Cup from Jan 1-9 and were put in Group A along with Norway, Chile and Spain when the draw was held earlier this month.

With Serbia, who won the inaugural ATP Cup in 2020, scheduled to open its campaign on Saturday, time is running out for Djokovic to play in Sydney and then in Melbourne, where he would have a chance to break a three-way tie for 20 major titles, currently shared with Roger Federer and Rafa Nadal.