Victorian state Premier Daniel Andrews said the man last worked at the Grand Hyatt Hotel in Melbourne on January 29 and anyone there was considered a casual contact.
More than 1,000 players, coaches and officials jetted into largely virus-free Australia last month for 14 days’ lockdown ahead of the opening Grand Slam of the year.
The Grand Hyatt was one of the designated hotels used.
“There is a number of about 500, 600 people who are players and officials and others who are casual contacts,” Andrews said in a late-night press conference.
“They will be isolating until they get a negative test and that work will be done tomorrow.”
But with test results generally returned within 24 hours, he said he did not expect the precautionary move to impact the Australian Open, which is scheduled to start on Monday.
“It may have an impact on tomorrow’s play in the lead-up events. But at this stage, there’s no impact to the tournament proper,” he told reporters.
Six ATP and WTA tournaments are currently being played at Melbourne Park to get players match fit for the Grand Slam after their fortnight in quarantine.
While most players were allowed out to train during their lockdown, 72 were confined to their Melbourne hotel rooms 24 hours a day after eight positive Covid-19 cases were detected on the charter flights that brought them to Australia.
Aggressive restrictions on incoming travel have helped keep the coronavirus at bay in Australia, making it one of the countries that is still able to have fans at sports events.
Andrews said tennis was not the most important issue.
“I must say that is important to us but the issues are much broader and that is about public health and public safety,” he said, but added: “This is one case, there’s no need for people to panic.”
Victoria had gone 28 days without a locally acquired infection, with the new case prompting a tightening of rules around mandatory mask use and a reduction in the limits of how many visitors are allowed in homes.