Atletico Madrid took control of Champions League Group D with a 1-0 victory over Bayern Munich at the Vicente Calderon, as Carlo Ancelotti suffered his first defeat in charge of the club.
Diego Simeone's side beat the German champions by the same scoreline in the first leg of last season's semi-final clash in April, and they followed that up with a deserved victory thanks to Yannick Ferreira Carrasco's pinpoint finish.
Bayern went into the game off the back of eight wins in a row in all competitions, but struggled to find any attacking cohesion despite enjoying the majority of possession.
Indeed, Atletico could have led by more before Carrasco's 35th-minute strike, with Fernando Torres twice spurning good opportunities and Manuel Neuer saving well to deny the goalscorer again.
Franck Ribery dragged a shot wide from close range and Thomas Muller missed a good chance from a header, but Bayern rarely had goalkeeper Jan Oblak concerned during what proved to be a fourth successive defeat in the competition on Spanish soil.
Antoine Griezmann spurned the chance to make it 2-0 when he blazed an 84th-minute penalty against the crossbar, but Atletico now top the group on six points, three ahead of Bayern, who sit in second place above Rostov and PSV following their 2-2 draw.
Atletico's defensive masterclass kept Bayern at bay in the last-four clash at the Calderon earlier this year, but Simeone's side had plenty of early pressure and only a smart block from Javi Martinez - following a loose touch - stopped Torres from opening the scoring from close range.
Oblak made a stunning reaction save to deny Muller on the volley after the Germany forward beat the offside trap, before Neuer sprung low to his left to block Carrasco's effort from the edge of the area.
Torres missed a glorious chance to break the deadlock after 22 minutes, heading against the post from just three yards out following Saul Niguez's flick, and Robert Lewandowski nodded a presentable opening into Oblak's grasp at the other end.
But Atleti got the lead they deserved after 35 minutes. Sloppy play from Xabi Alonso saw the ball break into Carrasco's path, and he drilled a low finish past Neuer and in off the base of the post from 20 yards.
Ribery scuffed a shot past the near corner after finding a rare pocket of space in the Atleti area, and Muller headed wide when unmarked at a corner just after half-time as Bayern looked for a decisive response.
Ancelotti introduced Arjen Robben just before the hour mark in a bid to inject some attacking verve, but Neuer was called upon to keep his side in the match when he dived to his left to parry Carrasco's drive from distance.
Bayern set up camp in Atleti's half in the closing stages, Lewandowski glancing a header just past Oblak's right-hand post, before Robben arrowed a low shot narrowly wide, but their attacking efforts remained largely laboured against a home defence brilliantly marshalled by Diego Godin.
Griezmann then squandered the chance to make the last few minutes comfortable, crashing his spot-kick off the woodwork after Arturo Vidal had barged Filipe Luis to ground, but Atleti held firm to extend their run to 26 wins in 31 European games on home turf.