Atletico Madrid won a La Liga derby against Real Madrid for the first time in six years on Sunday as a 1-0 victory left Diego Simeone's side on the cusp of securing Champions League qualification.
Yannick Carrasco's first-half penalty proved enough at the Wanda Metropolitano against a heavily weakened Real Madrid, who took the chance to rotate after their incredible Champions League comeback against Manchester City on Wednesday.
With Karim Benzema, Luka Modric and Thibaut Courtois among those on the bench for the already-crowned champions, Atletico took advantage, even if they missed a string of chances that made the contest far more uncomfortable than it needed to be.
Atletico sit fourth, six points clear of Real Betis in fifth, with three games left to play. Their better head-to-head record over Betis means they will be guaranteed to finish in the top four if Betis fail to win away at Valencia on Tuesday.
If Betis beat Valencia, Atletico can make sure of their spot themselves by winning away at Elche on Wednesday.
"It is very important to qualify and we have to get one more win in three games to achieve it," said Atletico captain Koke. "If we work like this, we'll get there."
Sevilla's place also looks almost sealed after a 1-1 draw away at Villarreal earlier on Sunday gave them a seven-point cushion over Betis.
Atletico had not beaten Real Madrid in La Liga since 2016 and not at home since 2015, while their last eight games in all competitions against their city rivals had brought two goals and no victories.
Ending that run will certainly bring much satisfaction to Atletico's fans and players but the bigger relief will be Champions League qualification, which has been in doubt for the duration of what has been an inconsistent and disappointing campaign.
Carlo Ancelotti made a raft of changes to his starting line-up as only Toni Kroos, Casemiro and Eder Militao remained from the team that pulled off the sensational victory over City.
It meant rare starts for the likes of Luka Jovic up front, Eduardo Camavinga in midfield and Jesus Vallejo at the back while Ukrainian Andriy Lunin made his first league appearance of the season in goal.
Lunin did nothing wrong but nobody stood out, with Camavinga out of sorts and Jovic replaced in the second half.
"We have rested some players, we have avoided problems, and we have given minutes to those who have had less," said Ancelotti. "It will be like this for the next few games."
Atletico's greater intensity showed in the first half as Angel Correa drove an early shot wide after a poor pass from Camavinga allowed Geoffrey Kondogbia to rob Kroos before Carrasco weaved through but flashed wide.