Plymouth fans boycotted a League Cup tie at Fratton Park.
The club blamed the Battle of Home Park for frightening them off.
The Argyle secretary Graham Little said: ‘We should have expected to run a dozen coaches to Portsmouth and had easily 500 fans at the game.’
But the club had just one official coach going to Fratton.
In the first leg, rival fans fought pitched battles in and around Plymouth ground and 20 were arrested by police.