As Borussia Dortmund prepare for their tempestuous Matchday 12 derby against Ruhr district neighbours FC Schalke 04, bundesliga.com turns its spotlight on the German game's ultimate local power struggle.
The fixture is one of the most passionately contested in world football and it means more to each set of fans than any other fixture on the football calendar.
A Revierderby refers to the meeting of Dortmund and Schalke, who are based 32 kilometres away in Gelsenkirchen. A number of other professional teams hail from the wider Ruhr region, but they have to make do with the tag 'minor Ruhr derby' for their various head-to-heads.
Other than their proximity, there was no particular trigger for a rivalry which, if anything, has only intensified over the years for two sets of fans who basically like nothing more than to put one over on their neighbours.