Pep Guardiola said Erling Haaland can become the Champions League's all-time top goalscorer after reaching 50 in record time in Manchester City's 2-0 win over 10-man Napoli.

Haaland reached his half century in Europe's elite competition in just 49 appearances before Jeremy Doku ensured Guardiola's men got their quest for Champions League glory off to a winning start

"The numbers speak for themselves and how fortunate we are to have him," said Guardiola.

Haaland moved to 12th in the all-time scoring Champions League scoring charts and is barely over a third of the way to Cristiano Ronaldo's record 141 goals.

But Guardiola believes the 25-year-old has time on his side to reach that milestone.

"Along with the two monsters of the past 15 to 20 years Ronaldo and (Lionel) Messi, Erling is there. In terms of goals he is unbelievable," added Guardiola.

"In that rhythm (he can break the record). If he can play 10 to 12 more years and maintain this progression, absolutely."

There was no fairytale return to the Etihad for Kevin De Bruyne as his night was cut short after just 26 minutes as a result of Giovanni Di Lorenzo's early dismissal.

De Bruyne was welcomed back like a hero just months after departing as one of City's greatest players in the club's history.

The Belgian's name rang around the Etihad before kick-off, while a series of banners paid hommage to the man who contributed nearly 300 goals or assists in 422 matches during his time in Manchester.

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Kevin De Bruyne's return to Man City lasted only 26 minutes / © AFP

However, Antonio Conte showed no room for sentiment as he sacrificed the 34-year-old to bolster his defence with the introduction of Mathías Olivera.

"I was very sorry I had to make that substitution, I also knew by taking him off we were going to miss some of the things he can give us," said Conte.

"But I don't really see that I had any other option. He understood why I had to make that decision."

- Napoli avoid humiliation -

The game changing moment came when Di Lorenzo made a desperate lunge to prevent Haaland running clear on goal and wiped out the Norwegian on 21 minutes.

Referee Felix Zwayer initially thought the defender had got a touch on the ball but was instructed by VAR to review and correct his error.

Napoli held firm until half-time thanks to some spectacular goalkeeping from Vanja Milinkovic-Savic.

The Serbian, who had a brief spell early in his career at Manchester United, produced excellent saves to deny Rodri, Nico O'Riley and Josko Gvardiol.

Even when Milinkovic-Savic appeared beaten in first-half stoppage time, Matteo Politano got back on the line to block Tijjani Reijnders' goalbound effort.

There was only one outcome once the Napoli rearguard was eventually breached 11 minutes into the second half.

Phil Foden's flick found Haaland who looped a header over Milinkovic-Savic for his 12th goal in seven games for club and country this season.

Doku then delivered the knockout blow with a brilliant individual run past three Napoli defenders before slotting coolly under the onrushing goalkeeper.

Ahead of a trip to title rivals Arsenal on Sunday, Guardiola could afford the luxury of resting Haaland and Rodri during the closing stages, which resembled a training exercise as City stroked the ball around at will.

Conte conceded the Italian champions were happy just to limit the damage in what is likely to be their toughest trip of the league phase.

"We didn't want to come out of this humiliated, because it could have happened," added Conte.

"They could have pulled our pants down and lost 5-0 or 6-0 and we avoided that thanks to our atittude."