Djokovic had been in a quarantine hotel in Melbourne the last few nights ... after Australian government officials canceled his visa shortly after his arrival in the country last Wednesday.

Authorities argued Djokovic did not meet the proper requirements to be formally granted an exemption to Australia's strict COVID-19 vaccination rules.

Djokovic, though, argued he did meet all the criteria ... saying he had been infected with COVID last month and therefore did not need to be vaccinated.

At a visa appeal hearing in an Australian courtroom on Monday -- a judge overturned the government's decision, pointing out that the 34-year-old had received vaccine exemption status from Tennis Australia and two medical panels prior to his arrival.

"The point I’m somewhat agitated about is what more could this man have done?" the judge said in the courtroom.

The judge's decision now paves the way for Djokovic to compete in The Open, which begins on Jan. 17.

"I'm pleased and grateful that the Judge overturned my visa cancellation," Djokovic said in a statement on Twitter following the decision. "Despite all that has happened, I want to stay and try to compete @AustralianOpen."

"I remain focused on that. I flew here to play at one of the most important events we have in front of the amazing fans."

There could still be more hurdles for Djokovic to leap ... Australian authorities have suggested they could still cancel his visa once again.

If that does happen, and Djokovic is deported, he could be faced with a 3-year ban from the country.

It remains unclear what the likelihood of a second cancellation is.