The issues arose in Korenmarkt, the city’s bar district, with police intervening after drinks glasses, chairs and punches were thrown.
Before the incident there had been a good atmosphere in the area and rival fans had spent much of the previous 24 hours drinking together.
Things deteriorated, however, around two hours before kick-off in the third qualifying round tie at the nearby GelreDome.
Riot police and horses were called in after clashes, with onlookers claiming they had come after provocation from Feyenoord supporters.
A group of people are understood to have charged into the square, where a number of Southampton fans are alleged to have been seen throwing chairs and fighting.