But in Haaland, he has secured arguably the most fearsome attacking threat in world football. And while he may not possess Messi's unique technical qualities, he is proving an irresistible match-winner to compare to the Argentina legend.
After hitting three against Manchester United in a 6-3 win on Sunday, he looked set to record his fourth hat trick of the season against Copenhagen.
Instead, Guardiola withdrew him, as City continued its demolition of the Danish champion without him.
Riyad Mahrez scored from the penalty spot 10 minutes into the second half after Marko Stamenic brought down Aymeric Laporte.
City could and should have added several more goals, with Jack Grealish repeatedly coming close either side of the interval - but Julian Alvarez made it 5-0 when turning home Mahrez's ball in the 76th minute.
Haaland scored after just seven minutes - powering a first-time shot past Grabara after impressive work from Joao Cancello.
He doubled the lead in the 32-minute - tapping into an empty net after Sergio Gomez' shot was parried by Grabara.
It looked like Haaland had completed his hat trick when City made it 3-0 six minutes before halftime - but Gomez's effort was diverted over the line by Copenhagen defender David Khocholava with the striker set to pounce.
Copenhagen coach Jacob Neestrup acknowledged that his team was powerless to stop a player of Haaland's prowess.
"We prepared, but he's a top class striker," he said. "I saw the goals and the second goal there was a shot and when you see the way he moves when the ball was on the way and he gets the rebound like it was natural.
"He's just a top-class player."
The win continued City's 100 percent record in Group G, three points clear of Borussia Dortmund, which beat Sevilla 4-1. They can secure qualification to the round of 16 with victory away to Copenhagen next week.