A Victorian man attended Melbourne's sold-out AFL preliminary final on Saturday night while infected with the measles, the state's health department says.
The man joined the more than 95,000 people at the MCG for the Richmond vs Greater Western Sydney game while infectious.
"When you're talking (about) a big crowd like that ... there's a possibility we will see more cases as a result," a Victorian Health Department spokesman told AAP on Wednesday.
A Victorian woman has also been diagnosed with the disease.
The diagnoses take the number of measles cases confirmed in Victoria in the past month to five.
The two Victorians travelled around the CBD, Richmond and North Richmond, Carnegie, South Yarra and visited a Balaclava gym while infectious between September 20 and 23.
"Measles has an incubation period of up to 18 days so those at risk of measles who visited these locations might show symptoms up until October," deputy chief health officer Dr Brett Sutton said in a statement.
"The illness usually begins with common cold symptoms such as runny nose, red eyes and a cough, followed by fever and rash."