The Australian Border Force is investigating reports that several individuals were allowed into the country with similar exemptions to Novak Djokovic before the Serbian tennis star was ordered to return home.
Australian immigration officials face accusations of scapegoating the world's number one tennis player after he was detained and ultimately ordered to leave Australia amid a furious row which has gripped the sport.
The saga could be set for further twists after the country's Home Affairs Minister Karen Andrews pledged to investigate reports which suggest that immigration laws may not have have been applied equally.
It was reported that at least two other people connected to the Australian Open were granted permission to enter despite having similar exemptions to Djokovic.
ABC reporter Andrew Greene tweeted: "Tennis Australia is believed to have granted exemption letters to two other individuals which don’t meet Australian government entry requirements. Australian Border Force officials are now investigating their cases."
This latest development could be be a potentially embarrassing situation for Australian officials, who on Wednesday dug their heels into the sand by canceling the visa of world number one Djokovic, who had received a medical exemption to defend his Australian Open crown.
It was declared by the border authorities that the Serb “had failed to provide appropriate evidence for entry” as he was detained for several hours by immigration officials before ultimately being ordered to leave the country.
Djokovic is challenging the ruling in court, with a hearing set for Monday, but has been warned by Australia's Prime Minister Scott Morrison that "rules are rules."
"Mr Djokovic’s visa has been canceled. Rules are rules, especially when it comes to our borders. No one is above these rules," he tweeted.
"Our strong border policies have been critical to Australia having one of the lowest death rates in the world from Covid, we are continuing to be vigilant."
It was later elaborated by Morrison that Djokovic's application was "insufficient" and that double-vaccination is required as a term of entry to the country.
"I also want to stress, that ultimately, this is the responsibility of the traveler. It is for the traveler to be able to assert and back up their ability to come into the country consistent with our laws," added Morrison.
This comes after the Australian leader had promised that Djokovic would be "on the first plane home" if it was found that his application details were not in order, a promise that he now seems set to deliver on.
However, reports in the Australian media suggest that two or more people connected with the Melbourne tournament were permitted into the country, leading to questions as to why the Serbian star, who has been seen as something of an anti-vax pariah in some circles, was supposedly singled out.
Australian Open chiefs had previously stated that a "handful" of anonymous players had been granted medical exemptions in a process they described as "equal" and "fair".
Serbian President Aleksandar Vucic waded into the row late on Wednesday, saying that his country "will fight" the "maltreatment" of their most famous sporting export.
This prompted Morrison into a denial that Djokovic was treated differently to any other traveler, or perhaps crucially, any other player – words which may now appear to be under increased scrutiny.
"When you get people making public statements of what they say they have and what they are going to do and what their claims are, they draw significant attention to themselves,” Morrison said.
“Whether they are a celebrity, a politician, a tennis player, a journalist, whoever does that, they can expect to be asked questions more than others before you.”
Elsewhere, former Australian Open director Paul McNamee tweeted that the situation "beggars belief".
"This is the only player I have ever known at the Australian Open who had his visa rescinded," McNamee told the local media.
"Djokovic rolled the dice whether an exemption would be approved, he received that. If he didn't get that, he wouldn't be coming to Australia.
"He was following the rules, players need to have confidence that the rules they abide by are going to be enforced...
"He's entitled to fair play, there's no doubt there's some disconnect between the state and federal government.
"I hate to think politics are involved, but it feels that way...
"Whether you like it or not, Djokovic doesn't make the rules. He deserves his day on court, not in court," McNamee added.