BY NICK ZAKHARIA AND EMILIE BAXTER

A violent brawl between fans at the MCG has marred the AFL season opener, with police arresting one man.

Witnesses said children were nearby when the fight broke out in the Great Southern Stand just before 10.30pm.

Carlton supporter John Rivett, 39, was just metres away from the brawl.

"It started in the aisle where people were exiting with families," Mr Rivett said.

"Just a verbal dispute between fans that escalated quite quickly."

Mr Rivett said about six people were involved, three from each competing teams' fanbase.

The violent outburst began between the two groups after Carlton’s 33-point loss to Richmond.

"The three [Richmond supporters] started running up the staircase to escape and I was trying to protect my 60 year-old mother," he said.

"If I didn't push her out of the way, they would have just bowled her over, I have no doubt about that. My mum was quite frightened by it all."

The brawl lasted about a minute before police intervened, pushing through crowds and climbing over seats to break up the fight.

A Victoria Police spokeswoman said one 19 year-old man, from Eltham, was arrested but later released after being hit with a $322 fine for riotous behaviour.

Tensions were running high before the first game of the season, with one Carlton fan posting the below threat to Richmond supporters in the lead up to the opening bounce.

MOJO is not suggesting it is related to the subsequent brawl.