A night that started with such promise soon crumbled away, City were on the front foot for most of the first half despite conceding after 17 minutes through a Fernandinho slip.
The turning point of the tie came early in the second, with City looking to build some resurgence following their good showing in the first half it all came undone within a matter of minutes.
A poor clearance from Claudio Bravo saw probably one of the last players City would want to pounce, Luis Suarez. Instinctively, Suarez looked to lob the ball in from the edge of the area leaving Bravo with two choices.
Either trust his defenders to be on hand to clear off of the line or commit himself and parry the ball. Choosing the latter saw the Chilean sent off for deliberate handling of the ball outside of his area.
This was the point Pep Guardiola felt the match was lost and he isn't wrong. All momentum City had accrued from the first half and beginning of the second had been wiped out by this red card derailing the team.
Whilst it is easy to be sympathetic towards Bravo for 'taking one for the team', wouldn't it have been better to have just left it and perhaps concede the second?
Guardiola seemingly remains faithful to his Chilean colleague, saying: "I spoke with him of course, he's disappointed because he's a huge professional, but it's all part of the game."
Despite City's best efforts Barcelona soon punished them further, Lionel Messi slotted home for his second just on the hour mark followed by completion of his hat-trick with just 20 minutes left.
Willy Caballero saving a somewhat poor Neymar penalty did raise spirits a little, the Brazilian however made amends just before the final whistle, slaloming through the City defense to complete what was a miserable evening for the Blues.
A crisis at City? Certainly not, but Guardiola will need to call upon all of his expertise to reinvigorate this side if they are to last the pace both home and abroad.