The Victorian Department of Health tweeted on Tuesday evening that one of the nine positive cases attended the match and was seated in the Great Southern Stand of the ground.
The match was attended by just 23,415 AFL fans despite the AFL allowing the MCG to be up to 85 percent full of its maximum capacity of 100,024 fans.
The news came after restrictions were tightened across Greater Melbourne on Tuesday as authorities scrambled to find the missing link in a fresh outbreak, prompting New Zealand to pause a travel bubble with the state of Victoria.
Authorities say the fan was seated in zone four, level one of the ground and those who were seated in a bay between M1 and M16 on their match ticket will be contacted directly by the Health Department, with the advice to isolate until they test negative.
They said CCTV footage would be reviewed to determine if the advice to isolate would need to be applied to other areas of the ground.
Anyone who attended the game and is displaying Covid-19 symptoms is being urged to isolate and get tested.
The Department of Health added that the AFL and MCC have run simulations for this scenario and contact information is linked to ticketing data via QR codes.
The case who attended the match is understood to be one of nine confirmed cases in the current coronavirus cluster.
Eight cases were confirmed on Tuesday with all nine infections recorded so far spread across three households.
Masks now have to be worn at all indoor settings by adults and children aged over 12.
Caps on private gatherings have been reduced with only five visitors allowed per day to a household, while outdoor events such as picnics or barbecues have a limit of 30 people.