City succumbed to goals from Brazilian pair David Luiz and Ramires as the rejuvenated champions leapfrogged the jaded Blues into the third place in the table that guarantees automatic entry.
Mancini, with great rivals Tottenham still to come to Eastlands, believes the remaining eight Premier League games still offer a golden opportunity to make sure of a top-four finish.
The Blues boss admitted: “This was an important game. If we had won or got a draw it would have been fantastic, but nothing has changed really. We’ve got eight (League) games to the end.
“We played three days ago against Kyiv with ten men, and in the last 20 or 25 minutes we were tired. Maybe we can train better because we don’t have the Europa League.”
City’s tired defending of a Didier Drogba free kick was the turning point as former Benfica star Luiz headed beyond Joe Hart to undo a sterling rearguard action.
Mancini added: “We were ready to change (with substitutions) when we conceded the goal. Until 70 minutes Chelsea had more of the possession but we didn’t concede anything. After the goal, it changed.”
But he refused to use injured skipper Carlos Tevez’s absence as an excuse. Tevez, who had a groin strain, scored twice in last season’s 4-2 win at Chelsea. Mancini said: “Carlos is a good player, but so are Dzeko and Balotelli.”
