Jack Kelly, 22, of Cracknore Road, Southampton, and Ewan Pilgrim, 23, of Landseer Road, Southampton, are accused of violent disorder after the large-scale fight on Terminus Terrace after Saints' match against Tottenham Hotspur in March 2023.
The two groups clashed near Oxford Street, and pint glasses, beer bottles and chairs were thrown over the course of seven-and-a-half minutes.
The pair attended Southampton Crown Court on Tuesday where a jury was sworn in.
Kelly and Pilgrim both deny the charge of violent disorder.
Opening the trial to the jury, Simon Jones, prosecuting, described what happened that day and Kelly's alleged involvement in the brawl.
He said that although Kelly did not throw any of the furniture or bottles, his presence as part of the group constituted involvement in the violent disorder.
Mr Jones said: "This is classically someone in it with his mates.
"He doesn't have to throw anything. He doesn't have to hit anyone with a punch. There are various degrees of involvement.
"He stays, intentionally helping and encouraging all of those who are involved in mob violence."
During the opening, the jury was shown a compilation video of the brawl.
The prosecutor said that Kelly's presence at the brawl is not in dispute.
Recounting the incident, Mr Jones described how the fight was organised by texts and voice messages between Tottenham fan Dante Lauder-Hawkins and Saints fan Kane Buckley after the match.
Kelly was among the Saints fans before they moved off to confront the Spurs fans, and Mr Jones said that he was aware they were going for a fight.
The trial continues, and Mr Jones is expected to continue his opening today.