All Guardiola’s pre-match complimentary talk about Napoli looked either kidology or just plain nonsense as City swept into a 2-0 lead after just 13 minutes.
Raheem Sterling and Gabriel Jesus continued their scoring streaks and City could have had more in a breathtaking first half an hour.
But once Napoli had shaken off the shell-shock from the early barrage, they showed the quality that has carried them to the top of Serie A on the back of eight straight wins and has so impressed Guardiola.
Ederson saved a first half penalty from Dries Mertens but Napoli stormed back after the break when Amadou Diaware pulled on back from the spot and a last-ditch block by John Stones denied Marek Hamsik a goal.
City held on to make it three wins out of three in Group H and effectively book their passage to the knock out phase of the Champions League.
City simply carried on where they left off against Stoke on Saturday and were two up in the first 13 minutes. In truth, they could have been home and hosed inside the first half an hour.
The goals were made and scored by the usual suspects.
Sterling spoke on the eve of this game of his determination to get into the box and score more goals.
And he was as good as his word in the eighth minute when he finished off a typically flowing City move.
Fernandinho, Leroy Sane and David Silva were all involved and, when Kyle Walker’s attempt had been blocked, Sterling followed up to score with his left foot from eight yards.
Who else but the majestic De Bruyne made the second with one of his slide-rule passes.
Fernandinho put him into space on the right hand side of his box and, just like he did for three of the goals against Stoke, he struck a perfectly weighted ball to set up the sort of chance Jesus does not waste.
It could have been worse for Napoli, De Bruyne’s first-time shot struck the underside of the bar and came down the wrong side of the line.
Then Sterling cut the ball back from the byline and Jesus’s shot on the turn was brilliantly parried by Pepe Reina but he needed Kalidou Koulibaly to stop the ball from crossing the line before hoofing it clear.
City looked like they wold score every time they surged forward and Ederson was not called into serious action until the 34th minute when he came out intercept Insigne’s dangerous cross.
Napoli had looked shell-shocked but began to show their quality towards the end of the half.
They wasted a chance to pull one back when Walker grappled with Raul Albiol and referee Antonio Lahoz pointed to the spot.
Ederson saved Dries Merten’s poorly struck penalty with his legs before Fernandinho reacted smartly to prevent Mertens from converting the rebound.
It was just about the perfect half for City but something had got into De Bruyne who was booked and then left the field att the break arguing with team-mates Silva and Fernandinho.
Despite their battering in the first half, Napoli came out for the second half encouraged by the fact that one goal would put them right back in it.
Stones performed heroics when Hamsik looked certain to score after City had been caught dallying on the ball and Mertens had squared the ball with Ederson out of his goal.
But Stones threw himself at the shot and the ball deflected off his midriff for a corner.
Napoli put a thrilling game right back in the balance thoughwhen Faouzi Ghoulam’s brilliant run into the box ended by Fernandinho’s trip.
Diawara took over spot-kick duties and showed Mertens how to do it. And City had to survive some anxious moments before securing tthe win on a night when they took their goals tally to 39 from 12 games in all competitions.