Isak also reportedly told Newcastle chiefs that he would never play for them again. Eventually, he got his own way with Liverpool having a £125million offer accepted in the closing stages of the window.
Louis Saha, who spent time with the Magpies on loan in 1999, was in a similar position to Isak when he left Fulham to join Manchester United five years later.
The Frenchman was not impressed with the way Isak conducted himself during his final weeks at Newcastle, telling Flashscore: “I was in the same position and I just asked to go because I wanted to join Manchester United.
“To be honest, I couldn’t see myself not playing for my club or putting myself in a situation where I was not professional. I think that was unprofessional. I’m under contract, I have to play.
“Regardless of whether I want to go and I think that it’s not fair because I’ve been promised something. I am under contract and this is my job, these things now happen more and more and that’s a sad thing.
“It doesn’t mean that the players need to show that they are very happy. I was not happy because when somebody says something about my career and promises me something, I’m ruthless. If I don’t like something, I’m going to say it.
“So this is part of our culture and how we’ve been trained. We are very honest with our feelings. But at some point there are limits to not cross and there is maybe something to be done.”
Isak could make his Liverpool debut against Burnley this weekend but Arne Slot has already hinted that it might be too early for him to start games.
“Don’t expect him to be [playing] every single game [with] 90 minutes on the pitch, that’s definitely not going to happen for the next few weeks,” said the Liverpool boss on Friday.
“He missed a proper pre-season. I think he missed three or four months of team sessions, so now we have to build him up gradually with us playing so many games and hardly any training time.
“That is going to be a challenge, but we have not just signed him for the upcoming two weeks, we have signed him for six years so this is what we have to keep in mind.”
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