Between 500 and 600 players, officials and staff at the Australian Open will go into self-isolation after a positive coronavirus case was identified at one of the event's quarantine hotels.
Thursday's matches at the Australian Open warm-up event at Melbourne Park have been cancelled as a result.
Victorian Premier Daniel Andrews confirmed on Wednesday that a 26-year-old man, who had been working as a resident support officer for the Australian Open, has tested positive for the virus.
Up to 600 people associated with the tournament have been identified as casual contacts of the man and will now need to self-isolate until they receive a negative test.
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A statement from Australian Open organisers on Wednesday said: "Health Authorities have advised us that a Hotel Quarantine worker has tested positive for COVID-19.
"Those associated with the AO [Australian Open] who quarantined at the hotel now need to be tested and isolate until they receive a negative test result.
"We will work with everyone involved to facilitate testing as quickly as possible.
"There will be no matches at Melbourne Park on Thursday 4 February 2021. An update on the schedule for Friday will be announced later today."
Andrews is hopeful the season's first Grand Slam will be unaffected, with the first round scheduled to start on Monday.
"At this stage there is no impact to the tournament proper," he said.
"I must say, that is important to us but the issues we are most focussed on are much broader and that is about public health and public safety and that is why we have really pounced on this very quickly."
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This year's Australian Open was pushed back by three weeks in order to allow players to complete a 14-day quarantine period on arrival in Australia.
Eight positive coronavirus cases have been identified from those tested, including Spain's Paula Badosa and the coach of 2019 US Open champion Bianca Andreescu, Sylvain Bruneau.
Up to 30,000 fans a day, around 50 per cent of the usual attendance, will be able to attend the tournament when it gets underway on Monday.
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