Barcelona started the match brightly, taking a deserved lead in the 19th minute. New signing Marcus Rashford provided a pinpoint first-time pass from the left flank, which Ferran Torres expertly slotted home to make it 1-0.
However, the lead was short-lived. PSG, despite missing several key attackers, equalised just before halftime through teenager Senny Mayulu.
The second half was a tense, back-and-forth affair with both sides pushing for the winner. PSG looked increasingly dangerous, dominating possession and piling on the pressure. The visitors came inches away from taking the lead in the 83rd minute when a shot from substitute Kang-In Lee cannoned off the post.
Just when it seemed Barcelona had weathered the storm, the killer blow arrived in the 90th minute. A rapid break saw Achraf Hakimi burst down the right flank and deliver a precise ball to Gonçalo Ramos, who calmly directed his shot past the goalkeeper to complete the turnaround for the French side.
The late goal seals a vital three points for Luis Enrique's PSG, who maintain a perfect start to their title defence with two wins from two matches. For Hansi Flick’s Barcelona, the loss is their first of the Champions League season and an immediate setback in their ambition to challenge for the title.