Ronaldo said he felt 'disrespected' and 'betrayed' by the club in a bombshell interview with Piers Morgan for TalkTV.
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It has been a tense season for the 37-year-old at Old Trafford that started with him wanting to leave and has seen him refuse to come on despite being instructed by manager Erik ten Hag.
Now Ronaldo has put his side of the story across before the Portugal superstar flies to Qatar for the World Cup, and it's likely to have signalled the end of his time at United.
Sheringham, who played 153 times for the Red Devils, says there is no coming back from this.
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He told talkSPORT Breakfast: "If I'm hearing it right that he doesn't respect the manager and has been disrespected. No chance he will play for Manchester United again, not after this.
"It sounds like there is going to be more that Piers Morgan will come out with. You cannot attack your football club and expect everything to be hunky dory when you come back from the World Cup."
Sheringham also questioned Ronaldo's behaviour this season and believes others at the club will have lost respect for him due to his actions.
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The former striker added: "Obviously Cristiano has his own ways of thinking, but when you join a football club, the football people want you to produce your best football moments. That's all it is really.
"I'd be very surprised if he was trying to be forced out. Disrespected… I don't know. If you are still performing at the highest level, people respect you.
"If you are doing things in and around the football club that you shouldn't be, like walking off down the tunnel when you should be part of the team, that's when people lose the respect for you.
"I think it works hand in hand."
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Ronaldo has just one Premier League goal this season in ten total appearances, with just four of them being starts.
The five-time Ballon d'Or winner is an undisputed legend of the game, but Sheringham feels he is past his best now.
He said: "You've got to realise yourself that you're not 29 any more, he's past his best and you've got to understand you are going to be used sparingly when you get to that age.
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"You cannot play every game. He wants to be the main man. He's fit and looks great, but it comes to all of us at some stage that you become past your best.
"If he was to realise that and let Ten Hag use him in the manner he feels fit, and he respects that and he obviously says he doesn't respect Ten Hag, and there's the problem straight away.
"That's the main issue the way I see it. If you don't have respect for the manager then it doesn't matter what else you do."