But the vaccine-sceptic Djokovic's high-powered legal team dramatically overturned the visa decision in court on Monday on a procedural matter related to his airport interview.
Now, Australian immigration minister Alex Hawke says he is considering cancelling the visa another time, as fresh doubts emerge.
Djokovic, a nine-time Australian Open champion, described reports about his post-infection outings in Serbia as "misinformation".
On the day after his positive test in Serbia, Djokovic appeared at a youth tennis event and at a ceremony to honour him with stamps bearing his image, both apparently without a mask.
Djokovic, who made no mention of the stamp ceremony, said he only received the PRC test result after attending the children's tennis event.
'Error of judgement'
But he admitted that he also went ahead with an interview and photoshoot with French sports newspaper L'Equipe on 18 December.
"I felt obliged to go ahead and conduct the L'Equipe interview as I didn't want to let the journalist down but did ensure I socially distanced and wore a mask except when my photograph was being taken," he said.
"On reflection, this was an error of judgement and I accept that I should have rescheduled this commitment."
The tennis ace also admitted a mistake on his Australian travel declaration, in which a box was ticked indicating that he would not travel in the 14 days before taking his flight to Melbourne.
In fact, social media posts and reports show he flew from Serbia to Spain during that period.
"This was submitted by my support team on my behalf - as I told immigration officials on my arrival," Djokovic said.
"My agent sincerely apologises for the administrative mistake in ticking the incorrect box about my previous travel before coming to Australia. This was a human error and certainly not deliberate."
Djokovic's public statement appeared to be aimed at swaying the government to let him stay in Australia.
Leading immigration lawyer Christopher Levingston said the government could cancel Djokovic's visa on narrow criminal grounds, for example, because the travel declaration was incorrectly completed.
But the immigration minister may also annul the visa on broader character grounds.
If Djokovic knowingly dodged Serbia's quarantine requirement for positive cases, he could be judged to be a risk for potentially not complying with public health orders while in Australia, Levingston said.
Various options to appeal would be open for both Djokovic and the government, but at the end of the day, the immigration minister can exercise his personal power to cancel the visa.