Lajovic will lead the Serbian team at the third edition of the 16-team men’s tournament, which the nation won back in 2020.

Djokovic’s absence was confirmed yesterday prior to the start of the event on January 1.

The tournament is expected to form part of players’ preparations for the Australian Open, with the first Grand Slam event of 2022 beginning on January 17.

Djokovic’s absence from the ATP Cup has increased speculation the world number one may miss the tournament, where he has won nine of his 20 Grand Slam titles.

Organisers of the first Grand Slam of the year have warned that all players will have to be vaccinated to take part.

Djokovic has declined to reveal whether he has received a COVID-19 vaccine.

Lajovic, the world number 33, said Djokovic is still hoping to play at the Australian Open.

"I don’t know the official reason but maybe the ATP knows," Lajovic said at a pre-event ATP Cup media conference, according to the Guardian.

"He said, ‘I’m not coming guys to the ATP Cup; we’ll see about the Australian Open’.

"I mean, he didn’t specify if he’s coming or not but that he’s waiting for a decision."

Djokovic has won the past three editions of the Australian Open.

The Serbian star is now the joint-record holder for men’s Grand Slam titles on 20, alongside Switzerland’s Roger Federer and Spain’s Rafael Nadal.

Federer is already a confirmed absentee from the men’s singles draw due to a knee injury.

Nadal’s participation remains in doubt following a positive test for COVID-19 after playing at the Mubadala World Tennis Championship, where he was making his comeback from a foot injury.

Russia’s Andrey Rublev, Canada’s Denis Shapovalov, women's singles finalists Belinda Bencic of Switzerland and Tunisia’s Ons Jabeur have tested positive following the event.

The players should be able to play if there are no complications in their recoveries from COVID-19.

Austria’s Dominic Thiem, the 2020 US Open champion, confirmed yesterday he had withdrawn from the Australian Open.

Thiem has not played a tour level match since June due to a wrist injury.

He will begin his season in Argentina.

Jennifer Brady, last year's Australian Open runner-up in the women’s singles, has been forced to withdraw from the tournament due to a foot injury.

The American joins compatriot Serena Williams, Canada’s Bianca Andreescu and the Czech Republic’s Karolina Pliskova as absentees from the women’s singles draw.