Dynamo Dresden fans were banned from their second-league team's match against Eintracht Frankfurt following previous violence which had already led to one so-called "ghost" match where no fans were admitted.
But around 400 made the trip to Frankfurt on Friday, and managed to get into the stadium, to the consternation of Eintracht CEO Heribert Bruchhagen, who said he thought he had done enough to keep them out.
“I did not expect that," he said. "We tried everything, and stopped advance ticket sales in time. At the end of the day I cannot explain how it came to this.”
Police used truncheons to separate groups of fighting fans after the match, which Eintracht won 3-0. They arrested 14 people, saying some Dynamo fans were found wearing Eintracht colours.
The streets around the stadium leading to the train station were filled with gangs, and police reported that Eintracht fans threw bottles and fireworks at their Dynamo rivals. The windows of a police car were smashed in, and stones thrown at a train in which Dynamo fans were sitting.
Eintracht fans have also been banned from their team's next away match against Union Berlin on March 26.
Football-related violence has been in the headlines recently after a group of Cologne fans attacked a bus carrying Mönchengladbach fans home from a match against a different team, forcing it off the motorway into a service station.