"Team Serbia will now be led by world number 33 Dusan Lajovic," organisers of the team event said in a statement.

There has been speculation over Djokovic's participation in the event and the Australian Open, which starts on 17 January, with the 34-year-old repeatedly declining to say if he has been inoculated against COVID-19, having previously expressed hesitancy over being jabbed.

Australian Open organisers have stated all participants must be vaccinated against coronavirus or have a medical exemption granted by an independent panel of experts.

Djokovic is on the entry list for the first grand slam of 2022, where he is the reigning champion, but whether he plays in Melbourne or not is still unknown.

He has won a record nine Australian Open titles, including the last three, and is tied with Roger Federer and Rafael Nadal in the all-time list - with all three winning 20 grand slam titles each.

Speaking to reporters earlier this month, tournament director Craig Tiley said: "Everyone who is coming in is vaccinated and there will be a small percentage - a very small percentage - that will have a medical exemption.

"So, if any player, fan (or) workforce is on site here, you're either vaccinated or you have a medical exemption that's approved and you're on the Australian Immunisation Register. That provides us with safety and an extra level of comfort on site.

"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 (it) 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."

Tiley expressed confidence that Rafael Nadal, who is currently isolating with coronavirus as he contemplates his return to the tour following a foot problem, will be in Melbourne.