Ronaldo warned "keep your mouth shut" after star sends Man Utd ultimatum

Cristiano Ronaldo has been warned to "keep your mouth shut" after reportedly sending Manchester United an ultimatum over the appointment of their next permanent manager.

The Portuguese superstar returned to Old Trafford in the summer transfer window after spells at Real Madrid and Juventus, but the homecoming has not been as happy as hoped.

United have long been out of the title race and currently sit more than 20 points adrift of Premier League leaders Manchester City, with Ole Gunnar Solskjaer having been sacked as a result.

Ralf Rangnick has been brought in to lead the team until the end of the season, but United are facing increasingly serious pressure from Ronaldo to get the permanent replacement for Solskjaer right.

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According to the Daily Star, Ronaldo is 'considering his future' and could depart Old Trafford if he is not a fan of United's next manager.

Though he has a contract until the summer of 2023, it is uncertain if will fulfil that contract amid United's search for a new boss.

But Ronaldo's ultimatum has angered many, with former England international Trevor Sinclair now blasting the 36-year-old.

Sinclair's former club City came close to signing Ronaldo in the summer before United beat them to his signature.

But the former winger believes that City have had a lucky escape amid the problems that Ronaldo is causing at Old Trafford.

And Sinclair has told Ronaldo to keep quiet after the reports that he could demand a transfer in the summer.

"I'm starting to think that Manchester City dodged a bullet by not signing Cristiano, I really think that," he told talkSPORT.

"You look at some of the players that are struggling for form at Manchester United, young players, Sancho, Rashford, they're really struggling for good performances.

"Course you can [blame Ronaldo for that]. Know your role, know your role. You're a footballer, you're hired by the football club.

"Keep your mouth shut because at times that's the best thing to do. He's causing a lot of problems at the football club.

"Not just his lack of goals in recent times, but the fact that Ole's gone and Michael went in and dropped him for a game."

Sinclair has also questioned if Ronaldo has United's best interests at heart, with the Red Devils facing a major battle to finish in the Champions League qualification places.

"I just feel it's been one of those signings where it looked good, but it's far from good," Sinclair added.

"For me, one of the reasons I think he may not have considered Manchester City, and it's certainly not winning trophies because he would have won a lot of silverware there.

"I think it's because he didn't want to be second fiddle to Pep. Whereas he could go into Manchester United, he could almost feel like he could bully Ole.

"And I think he just want to do what he wants for him and it's not the best for the club."