Ferguson's message to Ronaldo that left Portugal star in tears

In this file photo taken on May 12, 2013 Manchester United's Scottish manager Alex Ferguson holds the Premier League trophy at the end of the English Premier League football match between Manchester United and Swansea City at Old Trafford in Manchester, northwest England. [AFP PHOTO / Andrew YATES]

Cristiano Ronaldo and Sir Alex Ferguson had and have a brilliant relationship.

The pair worked with each other for nine years at Manchester United, where the enjoyed much success and won numerous trophies.

But the pair's relationship wasn't always as good as it is now.

Early on in Ronaldo's career the young Portuguese struggled to cope with Ferguson's 'hair-dryer treatment', and one particular exchange left him in tears.

The incident occurred during Ronaldo's very first season at Man United, following his £12million transfer from Sporting Lisbon in 2003.

Ronaldo didn't have a great game against Lisbon-based side Benfica, and Ferguson believed he needed to be reminded of his responsibilities and what it means to plan for Manchester United.

An excerpt from Guillem Balague's book Cristiano Ronaldo: The Biography reads: "In the dressing room, Ferguson could not contain himself: 'Who do you think you are?

"Trying to play by yourself? You'll never be a player if you do this!'

"Ronaldo began to cry. The other players left him be.

Cristiano Ronaldo in action for Manchester United before moving to Real Madrid. [PHOTO: AGENCIES]

"'He needed to learn,' said [Rio] Ferdinand. 'That was a message from the team, not just from Ferguson: everyone thought he needed to learn'."

Of course, as aforementioned, the pair's relationship wasn't always a sour one.

In fact, Ronaldo holds Ferguson in the highest regard, and in 2015, got emotional recalling the time the legendary United boss gave him time off to be with his dad.

Ronaldo said on the Jonathan Ross show: "In terms of personal stuff I just have to say, 'Thank you for what you did for me.'

"Especially, I remember, the thing that is in my memory, the time my father was sick in hospital and we were in a tough moment in the season.

"We had important games in the Champions League and league, and I said 'Coach, I need to go and see my daddy'.

"And I was a key player, a very important player. And he said 'Listen your family is the most important thing you have in your life.

"If you want to go three days, four days, five days, you can go.'

"This moment is what I keep with me, because it was the most important moment of my life. He shared it with me and this is why I respect him.

"And for me he is the best coach I ever had."