Second-half goals from Alex Grimaldo and Jonathan David were enough to give Atlético Madrid a richly-deserved 2-1 derby win over Real Madrid, despite a late header from Antonio Rüdiger.
The visitors offered very little, even before they went down to 10 men when Dean Huijsen was sent off for hauling down Giuliano Simeone in the incident which led to the penalty.
- Diego Simeone has 'huge respect' for José Mourinho as Madrid Derby looms
It had been more than 13 years since José Mourinho last faced off against Diego Simeone in this fixture, when Atlético beat Real 2-1 after extra time in the 2013 Copa del Rey final.
The two managers met again the following year, when Mourinho's Chelsea were knocked out of the Champions League in the semifinals at Stamford Bridge thanks to goals from Adrián López, Diego Costa and Arda Turan. That was the last time Simeone and Mourinho had been in opposite dugouts.
Both sides entered the game in decent if unspectacular form. Real had won five of their opening six LaLiga games -- against Espanyol, Real Sociedad, Malaga, Rayo Vallecano and Elche -- but had looked unconvincing at times, never more so than when they were beaten 1-0 at Real Betis, with Kylian Mbappé missing a late penalty.
It was a similar story in Mourinho's first Champions League game back in charge, as goals from Mbappé and Federico Valverde gave Real a 2-1 win over Inter despite the Spanish side being second best for much of the contest.
Atleti, meanwhile, started Sunday two points further back in fourth place with four wins from six -- over Málaga, Sevilla, Real Sociedad and Osasuna.
A chastening 3-0 defeat to Athletic Club in early September is the only major blot on their copybook so far this season.