Erling Haaland's agent, Rafaela Pimenta, has said that Manchester City are the most difficult club to conduct negotiations with.
In an interview with ESPN, Pimenta said the eight-time Premier League champions are "very serious, they're very organised. They're very big. They know what they're doing, they have a lot of experience, they don't really need anything, they have everything. So we don't have any leverage."
Her client Haaland signed a new nine-and-a-half year deal at the Etihad early last year, with sources telling ESPN that it was among the most lucrative deals in sports history.
"He's a lot like us [football agents], Pimenta explained. "In his way of being -- it's very informal, very comfortable, very relaxed, very low profile ... Football, for him, is the most serious game you can play.
"I think people often have the impression that the football player's job is easier than it actually is. I often say that high-performance football players have to be very intelligent, so don't underestimate the intelligence of those at the top of the pyramid. He has to be very dedicated," she added.
Haaland has already scored 109 Premier League goals in four seasons at the club -- with his new deal removing buyout clauses, according to ESPN sources.
He demonstrated some of his dedication to fitness and lifestyle in a "day in the life'" video on his personal YouTube channel, which has amassed over nine million views.
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In March, Pimenta rubbished claims that the Norway international had been in contact with Barcelona.
"Everything is going very well for him and we really have nothing to discuss about a transfer when everything is so good at City," she said at the time.
Pimenta -- who also represents Liverpool boss Arne Slot -- remained diplomatic when asked if the World Cup would impact any summer transfer moves.
"Look, it's hard for me to say that without causing gossip. I'm talking from my head without having any information," she said.
"I think Liverpool will make a lot of moves. Ajax we already know that it is making a lot of moves, everyone knows that. It is an important club, although it is certainly not a big club like Real Madrid and Barcelona."