Britain’s former world number one, Andy Murray, tested positive for the novel coronavirus recently and his participation in next month’s Australian Open is in doubt, local media reported on Thursday.

Thirty-three-year-old Murray, who is self-isolating and in good health, was awarded a wildcard to play in the main draw of the year’s first Grand Slam in Melbourne.

However, that could prove difficult with players and officials required to arrive in Australia during a 36-hour window from Thursday, as he is serving mandatory isolation of 14 days.

The players, who will be allowed to spend five hours outside their rooms during quarantine for training purposes, will play warm-up events at Melbourne Park from January 31 before the Australian Open starts on February 8.

Organisers, Tennis Australia, were not immediately available to comment.

Murray is currently ranked 123rd in the world.

American Tennys Sandgren got special permission to board a chartered flight from Los Angeles bound for the Australian Open on Wednesday in spite testing positive for COVID-19 earlier in the week.

A spokesperson for COVID-19 Quarantine, Victoria, said it was common among people who had previously tested positive to “shed viral fragments for some time – which can trigger another positive result”.

Three-time Grand Slam champion, Murray, pulled out of the season-opening Delray Beach Open in Florida earlier this month to reduce the risk of contracting COVID-19.

He had hip resurfacing surgery in early 2019 but made his comeback to win the Antwerp title nine months later.

He missed most of the 2020 season due to complications with his hip, and struggled for form on his return after the COVID-19 interruption.

Murray suffered a second-round defeat in the U.S. Open before falling in the opening round at Roland Garros.