Going in a goal down at half time Sunderland seemed to have hope for the second 45 minutes but City totally dominated after the break and added two more leaving Black Cats boss Roy Keane offering no excuses for the performance.
"To say I'm disappointed would be an understatement and we have no complaints about the result.
"City were stronger and quicker and looked dangerous on the break and there were not a lot of positives out there today.
"We had an off day and if that happens in the Premier League you get punished.
"It's a hard one to take and we'll have to learn the lessons from that and react in a positive way."