The Catalan giants took the lead in the 30th minute of the contest with Atletico through Pedri, but Rodrigo De Paul levelled the scores on the hour before Alexander Sorloth came up with a 96th-minute winner for Diego Simeone's side.
Atletico are now at the top of the La Liga table, three points ahead of second-placed Barcelona with a game in hand, while Real Madrid would also move above their Clasico rivals if they manage to beat Sevilla in Sunday afternoon's contest.
Barcelona have now lost back-to-back matches at their temporary stadium, having also suffered a 1-0 reverse to Leganes on December 15, while they have been beaten on five occasions in Spain's top flight during the 2024-25 campaign.
However, according to Sport, despite the recent setbacks, Flick has the full support of Barcelona, with the German's job not in doubt.
Flick 'not under pressure' at Barcelona
The report claims that senior figures at the Catalan outfit 'have absolute confidence' in Flick and are certain that he is still the right manager to lead the team moving forward.
Barcelona are in an excellent position in the Champions League table, sitting second behind Liverpool, boasting 15 points from their six matches in the competition.
Meanwhile, the team will begin their Copa del Rey journey for the 2024-25 campaign with a contest against Barbastro on January 4, with their next La Liga fixture taking place against Getafe on January 18.
Flick said that he was "very proud" of his team for their performance against Atletico, with the Catalan giants unfortunate to suffer a defeat to the capital outfit, who are now on a 12-game winning run in all competitions.
Flick "very proud" of his players for display vs. Atletico
"We played a great game. I'm very proud of my players but very disappointed with the result. Atletico are a very experienced team and have taken advantage of their chance," he told reporters.
"It was a very frustrating match. Pedri played incredibly, and so did Gavi. That's how we want to play. We will be back with a vengeance after Christmas.
"Not scoring is a problem but it was a fantastic game. It's not the same as what happened against Las Palmas or Leganes. We made two mistakes and they took advantage of them.
"The break will be good for us. We have to learn and play smarter. The quality in the game, I have nothing to say.
"Everyone has seen it. The one who scores the most goals wins. Dropping ten points at home is not normal and we will have to work on this."
Barcelona have ended the year with just one win from their last seven league matches, while they have now suffered three straight La Liga defeats at their temporary home.
Written by
Matt Law