Nick Kyrgios is a doubt for next week's Australian Open after testing positive for Covid-19.

Kyrgios, 26, has to isolate in Sydney for seven days and the Australian Open begins in Melbourne on Monday, 17 January.

He could still play if drawn in a first-round tie scheduled for Monday night or Tuesday.

"If all goes well I will see you all at the Australian Open," Kyrgios posted on social media.

Even if Kyrgios recovers and can travel to Melbourne in time, the world number 114 will enter his home Grand Slam with little preparation.

Kyrgios has not played competitively since September and withdrew from last week's Melbourne Summer Set because of an illness that sparked asthma issues, though he tested negative for Covid-19 at the time.

He was due to play his first match of the season against Italy's Fabio Fognini in Sydney but pulled out just hours before the start.

"I am feeling healthy at the moment with no symptoms," said Kyrgios, who has been vaccinated.

"I wish everyone all the best and to stay safe where you can."

Kyrgios recorded his equal-best Grand Slam result by reaching the quarter-finals of the Australian Open in 2015.

World number one Novak Djokovic's participation remains a major doubt, despite a judge overturning an Australian government decision to revoke his entry visa.

Judge Anthony Kelly ordered the release of the Serb from detention on Monday, but the 34-year-old has not been seen since and Immigration Minister Alex Hawke can still cancel his visa on new grounds.

Kyrgios has been a vocal critic of Djokovic in the past but said last week that Australia's handling of the visa dispute has been "really bad" and urged officials to "do better".