Former World No. 1 Andy Murray tested positive for COVID-19, putting his participation in the Australian Open in doubt.

Murray tested positive before his scheduled departure for Australia. Players are required to quarantine for 14 days and return a negative result on all COVID-19 tests before the tournament begins.

The Australian Open, delayed by the pandemic, is scheduled to start Feb. 8. Murray was set to take one of the tournament's charter flights to Australia this week.

"Andy Murray has advised that he has tested positive to COVID-19 and is isolating at home in the UK," the Australian Open said in a statement.

"Unfortunately this means he will be unable to join the official AO charter flights arriving in Australia in the coming days to go through the quarantine period with the other players."

Murray, a three-time Grand Slam champion, received a main-draw wildcard bid to the 2021 Australian Open. The 33-year-old was scheduled to compete at Melbourne Park for the 14th time. His most recent appearance there was in 2019, when he lost to Roberto Bautista Agut of Spain in five sets in the first round, then underwent hip surgery following the tournament.

Murray missed much of 2019 recovering from surgery, then had a setback that kept him out of the 2020 Australian Open.

Murray is tied with Andre Agassi and Ivan Lendl for fifth place on the all-time Australian Open wins list with 48.

"The AO fans love Andy, and we know how much he loves competing here in Melbourne and how hard he'd worked for this opportunity," the tournament statement said.

Murray pulled out of this week's Delray Beach Open, citing coronavirus concerns ahead of the Australian Open.

Murray is ranked No. 123. The Scot has won 46 career singles titles.