MELBOURNE: Novak Djokovic's bid to win a record-breaking 21st men's Grand Slam title at the Australian Open without a COVID-19 vaccination is in jeopardy again after Australia cancelled his visa for a second time on public health grounds.

Here is a summary of key dates in the still developing saga:

Dec 16: Djokovic tested positive for coronavirus, according to his affidavit to the Australian federal court. His accompanying PCR result by the Institute of Public Health of Serbia shows he was tested at 1:05 p.m. and the result time as 8:19 p.m.

Dec 17: The tennis star said he attended a charity event in Belgrade and social media posts show him maskless handing out awards to children. He said in a statement on Wednesday he did not get his PCR result until after the event. He said a rapid antigen test he took beforehand was negative.

Dec 18: Djokovic broke Serbia's isolation rules for a photoshoot and interview with L'Equipe newspaper. He said in his statement that he "felt obliged to go ahead and conduct the L'Equipe interview as I didn't want to let the journalist down."

Dec 22: He received a negative PCR result from the Institute of Public Health of Serbia, according to court documents.

Dec 24-25: Djokovic was seen in Belgrade, according to two eyewitness accounts https://www.reuters.com/lifestyle/sports/djokovic-travelled-across-europe-before-australia-trip-odds-with-declaration-2022-01-11 to Reuters. A video posted on social media on Christmas Day showed him playing street tennis in Belgrade.

Dec 30: Tennis Australia informed the world number one that he was granted a temporary medical exemption from the country's vaccine requirements on the grounds of previous infection. In a letter dated Dec 30, Australian Open organizers said this was granted by a panel of medical experts and reviewed by the state government of Victoria, where the tournament is held.

Jan 1: Djokovic told his agent to fill out his travel declaration to enter Australia. The declaration stated that he had not traveled in the 14 days prior to his expected departure from Spain on Jan 4. The Department of Home Affairs advised the agent that Djokovic met the requirements for quarantine-free arrival in Australia. The player later admitted the immigration form had contained an error in not saying he had traveled between Serbia and Spain in the 14 days before he departed.

Jan 2: Djokovic was issued with a border travel permit by the Victorian government. He was seen greeting a fan on video in Marbella, Spain.

Jan 4: "I'm heading Down Under with an exemption," Djokovic announced to the world in an Instagram post shortly before flying from Spain via Dubai to Melbourne. The impending arrival of the vaccine sceptic prompted a huge backlash in Australia, which has undergone some of the world's toughest COVID-19 lockdowns and where hospitalisation rates have hit a record high.

Jan 5: Djokovic touched down at Melbourne's Tullamarine airport at 11:30 p.m.

Jan 6: Australia's Border Force detained the tennis star in a room at the airport overnight, denying him permission to enter the country and notifying him of their intention to remove him. The Serbian president objected to Canberra.

Jan 7: Djokovic faced 72 hours over the Orthodox Christmas holed up in a hotel for asylum seekers after a court agreed to hear his appeal against his canceled visa.

Jan 10: In a virtual court hearing that saw pranksters hijack the live stream and protesters pepper sprayed outside his lawyers office, Djokovic was freed from detention. A judge quashed the government's decision to cancel his visa on the grounds it was unreasonable. Australian immigration minister Alexander Hawke said he would weigh the use of personal powers to deport him anyway. Just after midnight, Djokovic tweeted a photo of himself practicing at Rod Laver arena.

Jan 11: Social media posts and eyewitness accounts to Reuters contradicted Djokovic's immigration form declaration that he did not travel for 14 days before entering the country.

Jan 12: Djokovic posted a statement on Instagram apologising for the mistake on the form and for leaving quarantine to do a photoshoot with L'Equipe.

Jan 13: Djokovic was included in the Australian Open draw as top seed.

Jan 14: Immigration Minister Alex Hawke used discretionary powers to cancel Djokovic's visa for a second time, saying he may pose a health risk.