Tennis champion Novak Djokovic chances of playing in the Australian Open are on a knife's edge this morning with the Federal Court hearing now underway.

The World No.1 left Melbourne's Park Hotel about 8.30am today, where he had been staying under immigration detention after the Federal Government cancelled his visa for the second time.

The hearing in the Federal Court of Australia started at 9.30am AEDT. Follow key updates below.

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Judges want matter resolved by lunch

The Federal Court of Australia has heard the hearing between Novak Djokovic and Immigration Minister Alex Hawke could be resolved by lunchtime today.

The hearing is being conducted online, with judges Chief Justice James Allsop, Justice Anthony Besanko and Justice David O'Callaghan in three separate locations.

Djokovic is being represented by legal team Hall & Wilcox, including Paul Holdenson, QC, Nick Wood, SC, and Nik Dragojlovic

While Stephen Lloyd, Christopher Tran, Naomi Wootten and Julia Nicolic are representing Mr Hawke.

Background to case: Key details from lodged submissions

In a document lodged with the court on Saturday, Djokovic's lawyer claims the decision by Immigration Minister Alex Hawke to cancel the visa on Friday was "illogical, irrational and unreasonable".

Meanwhile, part of Mr Hawke's argument will be that Djokovic's presence in Australia "may foster anti-vaccination sentiment" and undermines the country's vaccination policies.

The minister has said this could specifically lead to:

• "An increase in anti-vaccination sentiment being generated in the Australian community, leading to others refusing to become vaccinated or refusing to receive a booster vaccine."
• "A reinforcing of the views of a minority in the Australian community who remain unvaccinated against COVID-19."
• "People deciding to not receive a booster vaccine."
• "Unvaccinated persons becoming very unwell and/or transmitting it to others."
• "Increased pressure placed on the Australian health system."

In his reasoning, Mr Hawke has also said he has considered that Djokovic has shown "an apparent disregard for the need to isolate following the receipt of a positive COVID-19 test result".

The minister has referenced the fact Djokovic attended an interview and photoshoot with French magazine L'Equipe on December 18 despite being knowingly positive for COVID-19.

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'Still 50-50'

Speaking to Today, former Department of Immigration senior official Abul Rizvi weighed in on the visa controversy, saying the hearing could "easily go either way".

"I would have to say it's still 50-50," he said.

"This is a complex one. My real concern is that the court may find the issues are substantially complex such that it is not able to make a final decision today.

"If it's unable to make a final decision, Mr Djokovic remains in detention until the court can make that decision.

"Well, that may well move into Monday. It could go into Tuesday, by which time Mr Djokovic's spot in the tennis may have to have been abandoned."