"I don't say my team failed," Mourinho said afterwards. "I would say that City played much better than us and deserved much more to win.
"The game was simple to analyse - they were the best team, and they won."
'Wenger is a specialist in failure'
Chelsea have beaten City twice in the league this season, including an impressive
1-0 win in Manchester on 3 February
that ended City's 100% home league record, but it is Manuel Pellegrini's side who will progress to the quarter-finals of the FA Cup after a convincing display.
Striker Stevan Jovetic, who also hit the bar, opened the scoring in the first half before midfielder Samir Nasri, making his return from injury, rifled home following a neat one-two with David Silva.
Mourinho felt City's second goal was offside but conceded it made little difference to the outcome in a game where his side only managed three efforts at goal, with none on target.
"They were the best team and when the best team wins I think football is at peace," he added. "Two weeks ago, the best team won and this time the best team won.
"What happened in this tie gives more credit to my players because it proves it is difficult to win twice against City in a season, and to win here.
"Was the referee's team poor in the second half? Yes. But even with perfect refereeing team, would Chelsea have won the game? No.
"Their second goal was an offside but they would win 1-0 anyway because we were never close enough to score or to be dominant or to scare City in the game."
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