There are growing fears NRL, AFL, Super Rugby and A-League matches will either be played in empty stadiums or cancelled altogether after a man with coronavirus attended last weekend's Melbourne Rebels match.

The man - who did not know he had coronavirus at the time he sat in the lower bowl at AAMI Park in Melbourne and watched the Rebels beat the Lions - was confirmed as one of three people diagnosed in the city on Wednesday morning, taking the total number of cases in Victoria to 21.

A coronavirus-infected fan attended the Rebels-Lions clash at AAMI Park on Saturday. Credit:Getty

The Olympic Park Trust confirmed the man had attended the match on Saturday night. While the next match at the venue - an A-League clash between Melbourne City and the Western Sydney Wanderers - will go ahead, the lower bowl will be intensively cleaned.

"Department of Health and Human Services has advised that the patron who attended AAMI Park for the rugby union match between the Melbourne Rebels and the Lions was diagnosed with COVID-19 overnight," an Olympic Park spokesperson said.