Real Madrid failed to defend their LaLiga title despite beating Villarreal 2-1 at Valdebebas.
Zinedine Zidane's men came into the final game of the season two points behind their city rivals but went behind 20 minutes in following Yeremi Pino's first-half poke past Thibaut Courtois.
Karim Benzema had a second-half header from Casemiro's cross ruled out for offside but equalised late on before Luka Modric's deflected winner.
However, Angel Correa and Luis Suarez scored for Atletico for a 2-1 win of their own, leaving Madrid's hopes ruined.
2020/2021 La Liga
2-1
Match Events
0' The match is about to start
19' GOAL! Real Madrid 0-1 Villarreal (Yeremi Pino)
24' CLOSE! Asensio's header over the bar
26' Parejo's handball overlooked by the ref
35' NICE TRY! Modric's shot wide out
44' Benzema's shot over the bar
49' Valverde's long shot wide out
56' OFFSIDE! Benzema's goal disallowed
66' What a miss from Benzema!
73' AGAIN! Benzema's shot wide out
83' CLOSE! Modric's long shot wide out
86' GOAL! Real Madrid 1-1 Villarreal (Benzema)
91' GOAL! Real Madrid 2-1 Villarreal (Modric)
Line-ups
Real Madrid XI: Modric, Benzema, Courtois, Casemiro, Varane, Odriozola, Asensio, Valverde, Militao, Vinicius, Miguel Gutiérrez
Subs: Ramos, Marcelo, Isco, Nacho, Mariano, A. Lunin, Antonio Blanco, Rodrygo, Altube
Villarreal XI: Albiol, Capoue, Parejo, Gaspar, Bacca, G. Rulli, G. Moreno, Trigueros, Pedraza, P. Torres, Yeremi Pino
Subs: Asenjo, Jaume Costa, Coquelin, R.F Mori, Alcacer, Moi Gómez, Moreno, R.Peña, P. Estupiñán, Dani Raba, Álex Baena, Fer Niño