Roy Keane has delivered a stark warning to Erik ten Hag and Man United over the ongoing circus surrounding Cristiano Ronaldo's future at the club.
The wantaway superstar's presence will continue to hang over the club even if he doesn't feature in their opening fixtures in the new Premier League season.
And now even Keane, one of his most ardent supporters, has acknowledged the five-time Ballon d'Or winner needs to act more professionally if he does remain at Old Trafford which seems increasingly likely with him drumming up minimal interest among Europe's elite clubs.
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He told Sky Sports: "You have to try and keep Ronaldo because he's a brilliant player, but we don't know Ronaldo's behaviour when he's back in the building.
"I don't think it's as big of a deal as everyone's making out. When you're a manager, trouble comes your way, he has to deal with it.
"I think it can work out well for United. My worry is if he stays and United don't start great, and he's resentful to the manager, then it could get ugly."
He added: "A lot of the issue is Ronaldo not playing in the Champions League for his ego, 'brand' or whatever.
"Why did his agent (Jorge Mendes) not have if Manchester United didn't get in the Champions League there's an option for both parties to have a look at it?
"If you've got this 'super agent' who has got unbelievable contacts and brilliant in terms of negotiations, why doesn't he have that in Ronaldo's contract?”
Upon taking over at Old Trafford, ten Hag had stated he was planning on Ronaldo being a key weapon for him.
However, his tone has grown more ambivalent over the past few weeks as he's seemingly grown weary of the 37-year-old's antics, namely when he left the stadium early while a friendly was still ongoing.
Although he has missed most of their pre-season through an excused absence over a personal matter, ten Hag may well have to give him at least a place on the bench in Sunday's opener against Brighton after Anthony Martial was ruled out with a hamstring injury.
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