World No.30 Amanda Anisimova has tested positive for COVID-19, Tennis Channel reported on Friday.
The 19-year-old has not confirmed the result but she is not competing at the WTA tournament in Abu Dhabi.
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In an Instagram post on Friday which included a crying emoji, she wrote: "I want to play."
The hard-hitting Anisimova is among a crop of rising American women making waves in the sport, a group that includes Australian Open champion Sofia Kenin, 22, and 16-year-old Coco Gauff.
Anisimova won her maiden tour-level title on the Bogota clay in April 2019 and reached a career-high ranking of 21 six months later.
The rescheduled Australian Open is due to begin on February 8 and Anisimova will be considered a doubt for the first grand slam of the year in Melbourne.
The news comes as the South Australian government announced it would offer support to the Australian Open by allowing up to 50 players to quarantine in Adelaide ahead of the grand slam.
Adelaide comes to Australian Open’s aid
With hotel rooms for international players in Melbourne nearing capacity with over 1000 arriving on charter flights next week, TA approached the South Australian government about hosting 50-plus players.
TA boss Craig Tiley said the SA government wanted some reward for their risk so they offered up an exhibition tournament in Adelaide on January 29 and 30 featuring the top three ranked men's and women's players.
That means Novak Djokovic, Rafael Nadal and Dominic Thiem could feature in the men's draw at Memorial Park, and Australian superstar Ashleigh Barty, Simona Halep and Naomi Osaka in the women's.
"We're right up to the edge of people that can quarantine in Melbourne so we needed some relief," Tiley told the Tennis Channel.
"We approached the South Australian government about the possibility of them quarantining at least 50 people, but they wouldn't have any interest in doing it because there's no benefit for them to do it to put their community at risk if the players then go straight to Melbourne.
"But it would be a benefit if they played an exhibition tournament just before they came to Melbourne, so the premier (Steven Marshall) has agreed to host 50 people in a quarantine bubble and then have those players play an exhibition event."
Tiley said the conditions for those players would be the same for the international players in Victoria.
The Adelaide-based players would then return to Melbourne Park with two WTA tournaments and two ATP events taking place as well as the 12-team ATP Cup, which starts on February 1.
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