Novak Djokovic's requests for access to his personal chef and a tennis court have been rejected by Australian officials, according to reports.
The Australian newspaper reported that the world tennis number one has been denied any "special treatment" during his stay in immigration custody.
Djokovic is beginning a third day in a Melbourne hotel that has doubled up as an immigration detention facility - a couple of miles from the luxury hotels where most Australian Open players are staying.
He is currently embroiled in a row over whether he is exempt from the country's COVID vaccination rules, and is facing deportation after his visa was cancelled.
Lawyers representing the 34-year-old are planning to appeal in court on Monday, and have been ordered to file a summary of their case today.
Djokovic, who has expressed scepticism about coronavirus vaccines in the past, wrote on Instagram yesterday: "Thank you to the people around the world for your continuous support. I can feel it and it is greatly appreciated."
The furore meant the Serbian tennis star was unable to celebrate Orthodox Christmas on Friday - an important religious holiday.
A priest from the Holy Trinity Serbian Orthodox Church in Melbourne had attempted to visit Djokovic, but was turned down by immigration officials because the hotel is under lockdown.
Supporters of the nine-time Australian Open champion have gathered outside the Park Hotel, waving banners as he remains cooped up inside.
'Maggots and mould in our bread'
About 30 asylum seekers are being housed one floor above Djokovic in the Park Hotel - and some of them have been held there for two years.
They were moved to Melbourne after being evacuated for medical treatment from Australia's controversial detention centres in Papua New Guinea and Nauru.
Even before Djokovic's arrival, the hotel had hit headlines amid allegations that maggots and mould were in the bread given to detainees.
Hossein Latifi told the Reuters news agency: "We are stuck in our room. There is no fresh air. We don't have any place for training. There is no gym here. It's very hard."
The 32-year-old, who is originally from Iran, added: "We are refugees, we are innocent people - we've not committed any crime. They just keep me like hostage here."
The third and fourth floors of the Park Hotel were damaged by fire on 23 December - and during an evacuation, some asylum seekers ended up becoming infected with COVID because they were held together with quarantining passengers who had tested positive.
'Challenging weeks' ahead
Daily numbers of coronavirus infections in Australia are repeatedly breaking records as the Omicron variant spreads.
An unprecedented 45,098 new infections were reported in New South Wales, the country's most populous state, on Saturday - up from 38,625 the day before.
The surge has prompted New South Wales to reintroduce some restrictions, with dancing and singing in pubs and nightclubs now prohibited.
Health officials in the state believe cases may only peak at the end of January, warning: "We have got some challenging weeks ahead of us. But we have been planning for this pandemic and continuing to reinvent ourselves for two years now."
Tennis rivals criticise Djokovic's treatment
Even some of those who have criticised the star in the past for his remarks on vaccines have spoken out against the way he is being treated.
Nick Kyrgios - an Australian player who called Djokovic a "tool" after he requested quarantine rules to be relaxed last year - tweeted: "Look, I definitely believe in taking action, I got vaccinated because of others and for my mum's health, but how we are handling Novak's situation is bad, really bad.
"This is one of our great champions but at the end of the day, he is human. Do better."