Lionel Messi opened the scoring on 20 minutes following a slip by Fernandinho but City ended the half the stronger. John Stones, Nolito and Ilkay Gundogan had all gone close for the visitors but the games complexion totally changed on 53 minutes as keeper Claudio Bravo made a mistake leaving him no option but to handle Luis Suarez's chip outside the area and a straight red card.
Eight minutes later Barcelona took advantage of this dismissal when Kevin de Bruyne gave away possession cheaply and once the ball was worked to Messi it was goal number two.
Number three arrived not long afterwards as Messi claimed the match ball helped by Luis Suarez and even a red card for Barca defender Jeremy Mathieu for a second yellow after downing Raheem Sterling failed to stop the Spaniards dominating their opponents.
Neymar even had the luxury of missing a penalty before he added the fourth in the final minute of the game meaning Barcelona have now not lost at home in 18 Champions League matches.
For returning former Barca manager Pep Guardiola this was a harsh lesson that whilst progress has been made with his new club they need to be clinical when on top if they are to compete with Europe's elite.
Barcelona: 4 (Messi 17, 61, 69 Neymar 89) (Mathieu red card 73)Man City: 0 (Bravo red card 53