Wayne Rooney and Co. have to be prepared to play second fiddle now that Zlatan Ibrahimovic is in town, with former Sweden international Pontus Karmak warning Manchester United's new striker must be the main man or there could be problems.
Ibrahimovic now calls Old Trafford home after departing French champions Paris Saint-Germain on a free transfer and the Swedish star has already made an instant impact at United, scoring the winner to help the club to Community Shield silverware last week.
While Rooney might be the captain, Karmak - who made 57 appearances for Sweden between 1990 and 2002 - said the United icon must be ready to relinquish his throne as top dog in Manchester as Ibrahimovic seeks to deliver the Premier League title to Old Trafford for the first time since 2013.
"Hopefully they get along, him and Rooney -- and if they do I think it is going to be the perfect match. If they don't, he is going to create a lot of problems," Kamark told the Mirror as the 47-year-old highlighted Ibrahimovic's spell at Barcelona.
"You can have both sides with Zlatan. He takes a lot of space and there can be a lot of trouble around him but he can also make things happen that would be difficult without him.
"He has been in all kinds of arguments. He called even Pep Guardiola 'The Philosopher' because [Lionel] Messi felt threatened about his superiority and Zlatan doesn't want to be number two.
"If someone comes in his way, he fights them. He can kick you down in training. He does whatever it takes to be on the throne. That can be for good and for bad -- especially if someone doesn't accept that.
"He always finds something because he can never be second best - Zlatan has to be number one."
Ibrahimovic and United kick-off their Premier League campaign at Bournemouth on Sunday and Karmak added: "I think he is a good player for Manchester United and see him almost like an Eric Cantona
"Man United have lost in recent years a little bit of their profile and slipped from being a winning team.
"When David Moyes came he even said in the derby against Man City, 'We are not the favourites'. You don't say that as a Man United player and Zlatan would never say that either.
"I think in that aspect he is a winner and he might help the team in the future. He is not young but if they can get the best out of Zlatan for a season or one-and-a-half seasons I think that could be very beneficial for Man United."