World number one tennis player Novak Djokovic's entry to Australia has been delayed over an issue with his visa.
The player arrived in Melbourne on Wednesday, where authorities noticed that his team had made a mistake on his application.
Djokovic is due to play in the Australian Open, after being exempted from vaccination rules.
But his team had not requested a visa that permits medical exemptions for being unvaccinated.
All players and staff at the tournament must be vaccinated or have an exemption granted by an expert independent panel.
Djokovic arrived in Melbourne's Tullamarine Airport on Wednesday and is awaiting a decision. He has not spoken about his vaccination status, but last year he said he was "opposed to vaccination".
The country's border force had sought clarification from the Victorian state government about his visa application, the Melbourne-based Age newspaper reports.
But state government Minister Jaala Pulford tweeted that his application would not be supported. Visa approvals were a matter for the federal government, she added.
The player was reportedly quizzed in a room in the airport. His current whereabouts and visa status remain unclear.
Meanwhile, Djokovic's coach and fellow Grand Slam champion Goran Ivanisevic posted a photo of himself on Instagram from a room in Melbourne, along with the caption: "Not the most usual trip Down Under."
Earlier, Australia's prime minister said Djokovic would be refused entry to the country unless he provided evidence that he could not be vaccinated for medical reasons.
Scott Morrison said the tennis player "could be on the next plane home" if the proof was insufficient.
The tournament's organisers say the defending champion has not been given special treatment, but the decision has infuriated many Australians. The country is seeing tens of thousands of Covid-19 cases for the first time after enduring some of the world's strictest restrictions.
Amid the controversy, Mr Morrison said the Serbian player would be required to present evidence upon arrival that he has a genuine medical exemption from vaccination. The Australian Open begins on 17 January in Melbourne.
"If that evidence is insufficient, then he won't be treated any different to anyone else," the prime minister told reporters. "There should be no special rules for Novak Djokovic at all. None whatsoever."
The comments seemed to represent a change in his position, after he said on Tuesday that Victoria's state government had provided the player with an exemption to enter the country and that officials would act "in accordance with that decision".