Violence erupted as Schalke won the 141st Ruhr derby 2-1 over rivals Dortmund, with around 200 people arrested and eight police officers injured in clashes.
A strong police presence - around 1,000 officers; twice as many as are on duty for a normal Bundesliga match - did little to mask the tensions as there were violent attacks hours before the game kicked off at 1530 local time.
According to local police reports, a restaurant was gutted by Dortmund followers "with furniture ripped apart and used as missiles against opposition fans and police''. One police car was damaged as mounted police, riot police and agents with dogs were brought in to keep the spectators apart.
Followers of both clubs attacked police who tried to segregate them in the Westphalian city and water cannons and tear gas had to be deployed to keep them at a safe distance. Mounted police were "attacked by Dortmund hooligans with cobble stones'', according to a police report.
There was further trouble inside the Westfalenstadion with Schalke fans lighting flares and displaying offensive banners, despite bans on such material.
And once the game had been completed, Schalke fans were marched out of the stadium under guard, but groups of fans continued to clash with police and Schalke manager Horst Heldt admitted the rioting had left him stunned.
"That's not what we imagined happening here," Heldt said. "Before the game, both clubs had made a statement that we hope the rivalry would be contained to the pitch. This is not nice and can't be accepted. Maybe at some point, we can express emotions through chanting and cheering."
During the course of the day, over 200 fans were arrested and eight police officers were injured, the city's police department confirmed.
"Perpetrators from Dortmund and Schalke have purposely undermined our security plans with their only goal being violent clashes with bystanders and rival fans," Dortmund's police chief Dieter Keil said.
"This has nothing to do with the enthusiasm for football and has nothing to do with what we want to see in Dortmund."
Information from the Press Association was used in this report