Novak Djokovic’s journey to Australia remains uncertain after he reportedly pulled out of the ATP Cup.

When he confirmed his participation for the multi-nation event that will take place in Sydney starting January 1, he had booked Serbia’s entry into the competition. Withdrawing now, at a time when no team can be replaced, has exposed a loophole in the tournament’s qualification process.

It also adds to the doubts around Djokovic travelling to Melbourne to defend his Australian Open crown.

Why has Djokovic decided to pull-out of the ATP Cup?

While it remains unclear, a member of Djokovic’s team was quoted by Serbian newspaper Blic, saying: “It is 99 percent sure that Novak won’t go to the ATP Cup. He is training (in Belgrade) but he has decided to give that tournament a miss.”

A video also appeared on social media of the 20-time Grand Slam champion rallying on a street in Belgrade with Serbian handball player Petar Djordjic on Christmas Day.

The Victoria state government had earlier made it clear that nobody – player, staff, officials, volunteers, fans – would be allowed to enter Melbourne Park without proof of being fully vaccinated. Djokovic however has been adamant in keeping his status disclosed, which is what has put his participation at the events in Australia in doubt.

There has also not been any information if Djokovic has received a medical exemption.

Will he skip the Australian Open?

Based on Djokovic’s father, Srdjan’s recent interview, the top seed will not give in to “blackmail” and will instead skip the event. As it stands, with Djokovic’s refusal to disclose his vaccination status, he will miss the year’s first Major – which he has won nine times including the last three editions.

However, last week Tennis Australia chief Craig Tiley confirmed that there will be a small number of unvaccinated individuals allowed in Melbourne Park with medical exemptions.

“Everyone who is coming in is vaccinated and there will be a small percentage – a very small percentage – that will have a medical exemption,” he said. “If Novak shows up at the Australian Open, he’ll either be vaccinated or he’ll have a medical exemption. (It’s) his choice on his medical condition, it’s his choice to keep personal and private like all of us would do with any condition we may or may not have. We are not going to force him or ask him to disclose that.”

Does his absence change the ATP Cup line-up?

It would have, but only if the withdrawal happened before December 7. Serbia – the winners of the inaugural edition of the event in 2020 only qualified this year because of Djokovic’s World No 1 rank. The same was the case for World No 15 Dominic Thiem, who withdrew last week due to non-Covid related illness.

Once the draw was made on December 7, all teams were locked in.

The qualification process is essentially based on the highest ranked player from a country. If hosts Australia’s highest ranked player is not slotted high enough in the 18-team event, they are given a wild card – which is the case this year.

Based on this process, there are a few unbalanced teams competing. Greece qualified because of World No 4 Stefanos Tsitsipas, but their next highest ranked player is World No 398 Michail Pervolarakis. Similarly, Chile (World No 17 Cristian Garin and No 139 Alejandro Tabilo), Georgia (Nikoloz Basilashvili 22 and Aleksandre Metreveli 569), Norway (Casper Ruud 8 and Viktor Durasovic 346) and Poland (Hubert Hurkacz 9 and Kamil Majchrzak 117) have lopsided squads. Meanwhile, with Thiem’s withdrawal, Austria is spearheaded by Dennis Novak, ranked 119.

Which countries have missed out?

The United States’ Taylor Fritz was the lowest ranked player, No 23, to secure qualification for his country. Serbia would not have qualified based on Dusan Lajovic’s 33rd rank, and Austria wouldn’t be there with Novak’s spot either.

Had Serbia and Austria withdrawn in time, they would have been replaced by World No 28 Grigor Dimitrov’s Bulgaria and World No 30 Marin Cilic’s Croatia, who were the Davis Cup finalists just last month.