Some 2000 AFL fans in Melbourne have been urged to get tested after a man with Covid-19 attended the Carlton-Geelong game at the MCG last Saturday.
Victoria recorded seven additional locally-acquired coronavirus cases connected to the NSW outbreak on Wednesday.
'DISGRACE': AFL world unloads over 'embarrassing' farce
'NEVER COME BACK': Footy icon Rex Hunt quits after on-air tirade
Four of the new cases are residents on the third floor of the Ariele Apartments in Maribyrnong, which has been in lockdown since Monday night after a visit from infected removalists.
Among those cases is a man in his 60s, who subsequently infected his parents, aged 89 and 90.
The man also attended the game between Carlton and Geelong on Saturday and Highpoint Shopping Centre on Friday.
Covid-19 Commander Jeroen Weimar urged anyone who has visited an exposure site or has symptoms to get tested.
“I appreciate this is concerning news,” he told reporters on Wednesday.
"The next two days are particularly critical. We are right on the heels of this particular outbreak.
“This is clearly a very rapidly moving situation, and we’re very keen to make sure we get a very firm grip of this as soon as we possibly can.”
Spectators who were on level two of the MCC Reserve have been classified as close contacts of the man who tested positive.
“There are caps at football for a reason, there‘s mask wearing indoors for a reason,” Weimar said.
“I need as much information as I can get to protect the Victorian community.”
War of words over Scott Morrison's support for NSW
The latest developments come as a war of words has broken out between the state and federal governments over financial support for NSW.
Prime Minister Scott Morrison on Tuesday announced a new federal support package following the Covid-19 outbreak in Sydney that has infected almost 700 people and claimed two lives.
The package will be jointly funded by the Commonwealth and NSW and offered to other states and territories if they have to impose extended lockdowns.
Premier Daniel Andrews' office issued a statement on Tuesday night accusing the federal government of favouritism towards NSW.
"It shouldn't take a crisis in Sydney for the Prime Minister to take action but we are seeing the same double standard time and time again," the statement read.
"His job is not to be the Prime Minister for NSW."
Treasurer Josh Frydenberg told ABC's 7.30 program people were "sick" of Mr Andrews' "whingeing and his politicking of the crisis".
"We've put in place a system with NSW that can be extended and expanded to other states should they incur a lengthy lockdown," he said.
Watch 'Mind Games', the new series from Yahoo Sport Australia exploring the often brutal mental toil elite athletes go through in pursuit of greatness:
Click here to sign up to our newsletter for all the latest and breaking stories from Australia and around the world.