Former tennis world number one Rafael Nadal on Monday revealed he had tested positive for the coronavirus.
The 35-year-old returned to Spain on Monday after an exhibition event in Abu Dhabi.
"I am having some unpleasant moments but I hope that I will improve little by little,” said Nadal on Twitter.
“I am now homebound and have reported the result to those who have been in contact with me.
The Mubadala World Tennis Championship had been Nadal's first taste of competitive action since withdrawing from the ATP circuit in August to nurse an injury to his left foot.
During the competition in the Gulf he lost his matches to Andy Murray and Denis Shapovalov.
Nadal had planned to contest the first Grand Slam tournament of the 2022 season at the Australian Open in Melbourne from 17 January.
But the illness might jeopardise his chances of competing at Melbourne Park where he has won one of his 20 Grand Slam trophies.
"As a consequence of the situation, I have to have total flexibility with my calendar and I will analyse my options depending on my evolution," Nadal added.
"Thank you all in advance for your support and understanding."
