Manchester City’s Pep Guardiola had an unhappy return to Nou Camp when his side were beaten 4-0 by Barcelona.
Lionel Messi was the hero as he struck a hat-trick and set up Neymar for the fourth goal.
Messi opened the scoring in the 17th minute but the game changed in the 53rd minute when former Barcelona keeper Claudio Bravo was sent off for handling outside the box.
Messi then added two more goals before providing play a key role in fourth when he was brought down leading to a penalty converted by Neymar.
A Mesut Ozil hat-trick saw the Gunners thrash Ludogorets 6-0 at the Emirates. The German international scored the last three goals after Alexis Sanchez,Theo Walcott and Oxlade Chamberlain had put Arsenal in the driving seat. Arsenal are on top of the group with a better goal difference than Paris Saint Germain who beat Basel 3-0.
Arsenal 6-0 Ludogorets
Paris Saint Germain 3-0 Basel
Dynamo Kyiv 0-2 Benfica
SSC Napoli 2-3 Besiktas
Barcelona 4-0 Manchester City
Celtic 0-2 Borussia Moenchengladbach
Bayern Munich 4-1 PSV Eindhoven
FC Rostov 0-1 Atletico Madrid