The never-ending derby.
The latter is how Marca described this capital battle last season, neatly encapsulating what this derby is and what it's become. Last term, Real Madrid and Atletico Madrid tussled a scarcely believable eight times across four competitions in a single campaign, with their two-season tally reaching 13. For two teams that didn't at all like each other beforehand, it's become the equivalent of handing each a sponge and asking them to share a daylong bath.
Now, it's here again on Sunday. Yes, again.
Tellingly, these meetings in recent years have not only shaped the derby's modern complexion but also entire seasons.