It started out as a nostalgic night for Manchester City but they could afford to celebrate their past. They were not harmed by it as their present and future dominated instead.

Kevin De Bruyne's return to the Etihad Stadium was an anticlimactic affair, cruelly curtailed. Erling Haaland was indirectly responsible for that, his pace and power leading to De Bruyne being sacrificed. Perhaps when the Norwegian enveloped his old sidekick in a hug at the final whistle, it was accompanied by an apology. While Napoli had signed City's greatest ever player, they could trace their defeat to the man surely destined to become City's record scorer.

And records tend to follow Haaland. His eighth goal in five games - including five for Norway - earned him a slice of Champions League history. He became the fastest player to 50 goals in the competition, taking just 49 games, smashing Ruud van Nistelrooy's previous best by 13 matches. Four days after a Manchester derby, City beat an earlier generation of United player.

Nor, indeed, could more recent exiles from United damage them. This was not a night for Rasmus Hojlund or Scott McTominay, just as the Belgian to score was Jeremy Doku, not De Bruyne.

What could have been a hazardous week for City has instead progressed swimmingly. De Bruyne, who only lasted 26 minutes before being hooked as Antonio Conte desperately shuffled his pack following the red card, was not the only departure. Pep Guardiola was able to remove first Rodri then Haaland and rest them ahead of Sunday's trip to Arsenal.

It was, though, all the consequence of the first man to leave the field. Which, in turn, reflected the way that Haaland can appear unstoppable, by legitimate means anyway, when isolated one against one. Napoli had started off looking organised and purposeful. When Giovanni Di Lorenzo was sent off for upending Haaland, however, a potentially even affair became an attack-against-defence exercise. Haaland altered the complexion of the match again, scoring with City's 21st shot. A side who are seeking to make amends for last season made the right sort of start.

City began their ill-fated Champions League campaign last year with a 0-0 draw against the champions of Italy, Internazionale. A repeat felt feasible during the Napoli resistance. Haaland had other ideas. Whereas, 12 months ago, City dropped two points and few realised how much peril it would put them in, now they go into consecutive away European matches with the cushion of three points. Napoli can at least console themselves with the thought they seem to have a strangely easy fixture list.

But Scudetto winners and Serie A leaders were shaping up well before a sliding Di Lorenzo sent Haaland tumbling, albeit while maybe getting a faint touch on the ball. The Norwegian brandished an imaginary card - avoiding getting a caution himself in the process - and got his wish when referee Felix Zwayer reviewed the incident and dismissed the Napoli captain.

The City supporters who enjoyed his exit soon faced the consequences. De Bruyne played two Champions League finals for City and each was ended early and in unfortunate fashion. So did his homecoming of sorts. Serenaded by the City faithful before kick-off and when he went off, De Bruyne was substituted so defender Mathias Oliveira could come on. It was an unsentimental decision by Conte; perhaps he figured that, with 10 men, a 34-year-old who has lost some of his running power represented a luxury.

Then Napoli's task became survival. City had 15 shots by half-time. Matteo Politano celebrated diverting Tijjani Reijnders' effort into Vanja Milinkovic-Savic's hands. The giant Serb, released by United a decade ago, was the reason parity was preserved for so long. He made a fine save from Rodri and still better ones to claw away Nico O'Reilly's header and deny Josko Gvardiol.

But part of Haaland's appeal lies in his penalty-box prowess against packed defences. When he excellent Phil Foden scooped the ball up, the Norwegian headed it in. The deadlock was broken. One goal soon became two.

Doku doubled the lead after a scintillating solo run, carrying on where he left off in the Manchester derby. After being baptised on Monday, he struck a few minutes after the arrival of Jesus: Juan Jesus, Napoli's third captain of the night.

Conte, who had won at the Etihad with both Chelsea and Tottenham, was ringing the changes by then. Hojlund had a lone and lonely vigil in attack and was booed off by the City supporters. McTominay was left to run many a mile for an outnumbered side.

Meanwhile, City had much to savour. Foden was influential again and came close to scoring when he angled a drive wide. Reijnders, named the best midfielder in Serie A last season even as McTominay won the division's award for the most valuable player, was excellent.

City, as Guardiola had noted on Wednesday, do not start this year's Champions League among the favourites. But after the ignominy of coming 22nd in the league phase last season, they are already positioned to do better. Thanks, in no small measure, to Haaland.

Erling Haaland ruins Kevin De Bruyne's homecoming to show how Man City have changed