Clifford Trammel said he suffered cuts to his face and mouth and lost four teeth after two men assaulted him. He said the Kansas City Chiefs were negligent in preventing the attack and later failed to step in and stop it.
In the lawsuit, Trammel said he was punched while trying to break up a fight between a friend and a Chiefs fan. He said he fell two rows from where he was standing and hit his head on the seats.
Fans at the Kansas Sampler on Monday said they planned to side with the Chiefs.
"Would a Chiefs fan do that if they went out to Oakland?, I don't think so," said one fan.
"If it has to do with the Raiders versus Chiefs, I'll support the Chiefs for it," said another.
The lawsuit said Chiefs security workers didn't step in to break up the fight. Trammel said the workers told him his injuries were what he gets for wearing the Raiders jersey to Arrowhead Stadium.
Trammel's lawsuit seeks damages of at least $250,000.