Real Madrid beat Atletico Madrid 2-1 in the Champions League.
Yesterday, the leaders of both teams called for calm to the fans, stating, "We are competitors, not enemies."
1,000+ security personnel were working at the stadium to ensure the smooth running of the match.
These teams have met four times in the Champions League, with three matches ending in a 1-1 draw.
Rodrygo and Brahim Diaz stood out for Carlo Ancelotti's team, while Julian Alvarez stood out for the visitors.
In parallel matches, London's Arsenal defeated PSV 7-1 in an away match, while Borussia Dortmund and French Lille drew 1-1.
The return matches will take place next Wednesday.