The Spanish star made his return to tennis at the Mubadala World Tennis Championship exhibition event in Abu Dhabi, having spent four months recovering from a foot injury.

The 35-year-old admitted after the event he could not guarantee his participation at the Australian Open as he continues his recovery.

Nadal has now confirmed a positive test for COVID-19, adding further doubt to whether he will compete at the first Grand Slam event in 2022.

"I wanted to announce that on my return home after playing the Abu Dhabi tournament I have tested positive for COVID in the PCR test that has been performed on me when I arrived in Spain," Nadal wrote on social media.

"In both Kuwait and Abu Dhabi, we passed checks every other day and all came back negative, the last one being on Friday and having the results on Saturday.

"I'm having a few unpleasant moments but I hope to improve little by little.

"I am now confined at home and have reported the result to people who have been in contact with me.

"As a result of the situation, I have to have total flexibility with my calendar and I will analyse my options depending on my evolution.

"I will keep you informed of any decisions about my future tournaments!

"Thank you all in advance for the support and understanding."

Austria’s Dominic Thiem, the 2020 US Open champion, has withdrawn from two warm-up events in Australia after suffering from a cold.

Thiem said he would not be in the physical condition to compete at the ATP Cup and Sydney ATP 250 but would confirm whether he will play the Australian Open by the end of December.

Swiss star Roger Federer is already a confirmed absentee from the men’s singles draw due to a knee injury.

Jennifer Brady, last year's Australian Open runner-up in the women’s singles, has been forced to withdraw from the tournament due to a foot injury.

The American joins compatriot Serena Williams, Canada’s Bianca Andreescu and the Czech Republic’s Karolina Pliskova as absentees from the women’s singles draw.

Organisers of the first Grand Slam of the year already warned that all players will have to be vaccinated to take part at the Australian Open.

France’s Pierre-Hugues Herbert, who won the men’s doubles title at the event in 2019 with Nicolas Mahut, became the first player to confirm they would not travel due to being unvaccinated.

Speculation has persisted over whether men’s world number one Novak Djokovic will compete at the tournament amid the policy.

The Serbian has repeatedly refused to reveal whether he has received a COVID-19 vaccine.

Nine of Djokovic’s 20 Grand Slam titles have come at the Australian Open, including winning the past three editions of the event.