Goals from Mario Balotelli, Micah Richards and Sergio Aguero inflicted Newcastle’s first defeat for the Blues, whose flying 12-match start is a record for the Premier League.
But manager Mancini already has his eye on Tuesday’s crucial group match in Italy, which has become an unofficial decider for the second qualifying place behind Bayern Munich.
The Blues boss said: “The feeling is good for Napoli. The team has improved a lot in the Champions League. But I know what we will find in Naples, they are playing very well at home.
“If we want to win there, then we will have to play better than this afternoon.”
Mancini shuffled his pack in a bid to rest some of his stars, with both David Silva and Gareth Barry only getting into the action in the second half with City heading for victory.
Aguero limped off before the end, but Mancini said: “It was nothing serious. He was tired, he flew I don’t know how many miles and arrived back on Thursday afternoon.
“David for me could play in all the games, but sometimes he must rest. He arrived on Thursday from Costa Rica. Gareth, the same, he played in two matches.
It’s always difficult after an international break, but I wasn’t worried
“I told the guys before the game that it would be difficult, that they have good players who are playing very well and that we needed to play very well.
“We had a lot of possession, scored three goals and had a lot of chances. I hope we can continue like this, but in the next 28 games there will be one that we lose.”
Balotelli, the new darling of Italian fans, raised eyebrows with a showboating penalty to put the skids under Newcastle, who hit a post before Dan Gosling’s late consolation.
Mancini said: “Mario is fabulous. It’s impossible for him to miss a penalty, I don’t know why! But he takes them very well.
“He’s a very important player for us, and he is becoming better and better. I’ve told him not to waste his talent, and that how good he becomes is up to him.”
