Ansu Fati’s thunderbolt in the second-half ensured the visitor took all three crucial points to boost its chances of qualifying for the knockout stages.
Incredibly, it was Barça’s first away win of the season after a string of poor performances which subsequently saw previous manager Ronald Koeman sacked.
The Catalan club’s caretaker coach Sergi Barjuan has taken charge while the blaugrana confirm Koeman’s replacement, with reports that former player Xavi is lined up to fill the void.
“We all knew that we had to win at any cost. The players were nervous before the game and you look at them now and their faces are different. Winning always helps and I hope we keep momentum for the next game,” Barjuan told reporters.
Barcelona sits second in Group E behind Bayern Munich, having lost both of its first two matches in the competition this season.
‘The best forward in the world’
Bayern, meanwhile, have already qualified for the Round of 16 after a thumping 5-2 win against Benfica on Tuesday.
Star striker Robert Lewandowski was on the scoresheet yet again in what was his 100th Champions League game, scoring a brilliant hat-trick.
The Polish superstar has now scored 81 Champions League goals in his career, including four hat-tricks.
Bayern head coach Julian Nagelsmann said Lewandowski, 33, should be aiming to reach the 100 goal landmark and called his player the “best” forward in the world.
Only Lionel Messi and Cristiano Ronaldo have scored more than 100 goals in European football’s most prestigious club competition but Nagelsmann would not be drawn into comparing Lewandowski with the two.
“I think all three were very impressive players over the last few years,” Nagelsmann told reporters after the match.
“I believe that Lewy can achieve a lot, also at an older age, because of his physique, lifestyle and the way he lives as a footballer.
“He will continue to be the best forward in the world because he does everything to keep it that way.”
However, it wasn’t all good news for Lewandowski who missed a penalty against Benfica on Tuesday – his first ever miss in the Champions League.
His limp attempt was easily saved by goalkeeper Odysseas Vlachodimos and the miss seemed to take the edge off an otherwise perfect evening.
“I do not know if it was the perfect game because I did miss a penalty,” Lewandowski said after the match.
“But better to miss early than late in the game. Luckily, we scored several more goals and got the three points.”
He added: “To be honest, I never thought I would ever play so many games in the Champions League and score so many goals.”