Matchday 3 of the 2016/17 UEFA Champions League was completed on Wednesday night with the second lot of fixtures.
In Group A, Arsenal flexed their muscle with a dominant 6-0 demolition of Bulgarian minnows Ludogorets Razgrad at the Emirates Stadium.
A second-half hat-trick from Mesut Ozil - his first in professional football - put the gloss on an already successful night which had the Gunners on fire with quality goals from Alexis Sanchez, Theo Walcott and Alex Oxlade-Chamberlain prior to the the German's treble.
Benfica picked up their first win of their top flight European campaign with a 2-0 win over Dynamo Kyiv in Ukraine to keep their qualifying hopes alive.
It was a dramatic night on Pep Guardiola's return to Catalonia which saw City keeper Claudio Bravo sent off for a brain fade before Barca turned on the style through Lionel Messi, who helped himself to get another hat-trick, while Neymar was also on target despite seeing a late penalty saved by Willy Caballero.
The Germans beat Celtic 2-0 at Parkhead to pick up their first lot of three points for the tournament.
The next Group A to D fixtures take place around Europe on Tuesday, November 1.
2016/17 UEFA Champions League - group stage
Barcelona (ESP): 4 (Lionel Messi 17'/61'/69', Neymar 89', missed penalty: Neymar 87', red card: Jeremy Mathieu 73')
Manchester City (ENG): 0 (red card: Claudio Bravo 53')
Camp Nou, Barcelona, Spain - 96,290