The British tabloid newspaper claims Ronaldo had grown apart from his team-mates at Old Trafford.
The United players were unhappy after Ronaldo tried to single-handedly win the Champions League final over Barcelona last month.
A United insider told the News of the World: “To many, that was the final straw and showed what he had become.
“Wayne Rooney had to change position three times to accommodate Ronaldo. The experienced players in the squad had seen it coming and weren’t happy about it.
“Ronaldo had been getting more and more temperamental in training and the others were getting fed up with him. They knew his mind was elsewhere and they thought he was becoming a distraction.
“The senior guys couldn’t believe it when he threw the tantrum during the Manchester City game.”
