Although Manchester United fans are understandably excited by the prospect of Cristiano Ronaldo returning to Old Trafford this summer, they do seem to be forgetting one rather important thing.

Jose Mourinho is the current manager of United, not Sir Alex Ferguson, who Ronaldo called his ‘father figure’ during his first spell with the Red Devils.

Ronaldo worked under Mourinho for three seasons at Real Madrid, but their working relationship deteriorated rapidly during the 2012-13 campaign.

Mourinho fell out with just about everyone at the Bernabeu during his third and final season with the Spanish giants, including the team’s star player.

And shortly after he left the club, Mourinho took a parting shot at Ronaldo via the Spanish media.

What Mourinho said about Ronaldo when he left Madrid

The Portuguese coach claimed he fell out with Ronaldo because his compatriot “thought he knew it all”.

“He (Ronaldo) had three great seasons with me, I don’t know if they were the best in his career because at Manchester United he had great seasons too,” Mourinho told Spain Intereconomia, per the Daily Mail, in June 2013.

“But I think we found for him a tactical situation that helped him express himself on the pitch perfectly as shown by goal figures.

“The only problem has been that a coach criticises him from a tactical point of view trying to improve him and he has not accepted it well thinking, perhaps, that he knows it all and that the coach could not help him become any better.”

Ronaldo was prolific under Mourinho

Indeed, Ronaldo enjoyed three of his best goalscoring seasons under Mourinho.

He netted 53 goals in 54 matches during Mourinho’s debut campaign at the Bernabeu; 60 in 55 in the following season, and then 55 in 55 during the 2012-13 season.

When Mourinho and Ronaldo almost came to blows in 2013

Mourinho found himself under increasing pressure during his last season in charge of Los Blancos and almost came to blows with Ronaldo during the team’s Copa del Rey quarter-final match against Valencia in January 2013.

This is according to the Spanish football journalist Guillem Balague, who described the moment they clashed at half-time in his 2015 biography on Ronaldo.

Balague, per the Telegraph, wrote: “With 10 minutes remaining, the coach very pointedly told Cristiano Ronaldo to track back. He also reprimanded him for hurriedly taking a throw-in that Mesut Özil was unable to control, allowing Valencia to break and provide the final fright of the match.

“Mourinho, whose blood was no longer boiling by the time he reached the dressing room, reminded Cristiano of the reason for the instruction on the pitch: ‘If they get a goal against us…’

“The player, unable to contain his fury, got up from the bench where he was changing and began shouting, ‘After everything I’ve done for you, this is how you treat me! How dare you say that to me?!’

"The dressing room turned deadly silent. Mourinho tried to remain calm. ‘I was saying it for the team, because the team needed you to track back.’

“As he could see Cristiano had no intention of calming down, he gradually retreated. Soon after, he approached the forward again to resume the conversation with less tension. But Ronaldo fired back angrily. Mourinho was unable to contain himself any longer.

“‘Just so you know,’ he shouted for everybody to hear, ‘many think like me here, but don’t dare say it, they don’t have the balls to tell you.’

“Many of the players who witnessed the scene had demanded that Mourinho, either directly or through the coaching staff, ask Ronaldo to defend more. The situation escalated to the point where Cristiano had to be held back (some sources say by Casillas, others say by Arbeloa and Khedira, or even Sergio Ramos) to prevent the pair from coming to blows.

“Ronaldo took what should have been understood as a tactical comment as a personal attack. The relationship between Mourinho and Ronaldo would never be the same again.”

Would Mourinho work with Ronaldo again?

Whether Mourinho is prepared to work with Ronaldo again is unclear, but United surely won’t waste the chance to bring him back to Old Trafford if the opportunity arises this summer.