Atletico Madrid slumped to a surprise 2-0 defeat at Bayer Leverkusen in the Champions League on Tuesday thanks to late goals from Robert Andrich and Moussa Diaby.
The Spanish side were left reeling after Leverkusen struck twice in the last six minutes to claim only their second win of the season and leapfrog Atletico into second in Group B.
"I'm so proud of the team. Getting a result against a side like Atletico will do us a lot of good, especially given the phase we are in at the moment," said Leverkusen defender Jonathan Tah, whose side have lost six of nine games in all competitions so far this season.
Atletico captain Koke told Movistar+ his side would have to be "self-critical" after letting the game slip away from them late on.
"We felt like we were in control, and then they hit us with two counter-attacks," he said.
"We should have given more today, we have to be self-critical."
Andrich had an early chance to give luckless Leverkusen the lead, smashing the ball over the bar from close range after just seven minutes.
Atletico were unfortunate not to be given a penalty after an apparent handball from defender Edmond Tapsoba midway through the first half.
After a brief discussion with the video assistant referee, English official Michael Oliver decided against a spot-kick, despite the replay showing that the ball had struck Tapsoba's outstretched arm in the box.
"The referee didn't tell us anything about the decision, he simply told us to carry on playing," said Koke.
The hosts should have taken the lead shortly after half-time, but hit the woodwork twice within a matter of seconds.
Patrik Schick hit the bar from point blank range in a one-on-one with Atletico keeper Ivo Grbic, before Adam Hlozek headed the rebound onto the post.
Both sides had further chances to take the lead before Andrich and Diaby produced two smash-and-grab goals in the final minutes of the game.
Andrich curled the opener into the bottom corner from the edge of the area on 84 minutes, before Diaby tucked in the second at the end of a brutal counter-attack three minutes later.
Atletico head to Group B leaders Club Brugge in their next Champions League game on October 4, while Leverkusen head to Porto.