Pompey licensees fear their takings will be hit after Portsmouth Football Club announced it is to open a 500-capacity beer tent at its ground on match days.
The marquee opens for the first time this Saturday.
It will have a massive effect on my pub - match days are the busiest days of the week Gary Whittingham, licensee of Mr Pickwick's.
Gary Whittingham, licensee of Mr Pickwick's told the Portsmouth News: "It will have a massive effect on my pub - match days are the busiest days of the week.
"We can make about £3,000 on a good day.
"I really think the club should have told us if they were trying to step on our territory.
"I just hope a lot of fans show loyalty and keep spending their money in our pubs.
"But if Pompey undercut us on price it will make things very difficult."
The marquee will open at 11.30am and close at 7pm - it willl also be closed during the match.
The club's marketing director, Paul Bell, told the paper: "Our only concern is the fans and giving them what they want."