The world number one tennis player Novak Djokovic has won his case against deportation from Australia on the country's strict COVID-19 vaccination rules.

Djokovic's fans celebrated Monday outside an immigration hotel in Melbourne where he had been detained. Federal Court Judge Anthony Kelly said the Australian government's decision to cancel his visa was 'unreasonable.'

He said that the Serbian tennis star was not given enough time to speak with tournament organizers or his legal advisers after he was detained Wednesday at Melbourne airport, a standard treatment for an "unlawful non-citizen" according to Australian law.

He had flown to Australia believing he had an exemption from the country's COVID-19 vaccination regulations, which state all foreign nationals entering the country must fully be inoculated or have a medical waiver.

Djokovic said he had contracted coronavirus in December, which gave him the right to apply for an exemption. However, Australian border authorities had said that the tennis star had not met immigration regulations and would be deported.

But his lawyers told the court that the decision to revoke his visa was 'illogical, irrational and legally unreasonable.'

'This is the outcome I expected, yes,' Immigration lawyer John Findlay told the Australian Broadcasting Corp. 'Mr. Djokovic's lawyers put a very compelling case. The main thing that the court was concerned about was the unfairness - the manifest unfairness - to Mr. Djokovic about the way the officers at Melbourne airport conducted themselves.'

Djokovic has been released from detention and will likely be allowed to defend his Australian Open title. He has won the event nine times.

Should he triumph at this year's tournament he will become the most successful men's grand slam champion with 21 titles. However, Australia's immigration minister Alex Hawke has the ability to intervene again and order his deportation.

Under Australian law, the minister has exceptional authority and discretion to cancel a visa.