considered quitting football before securing his move to in 2003 as he was being 'bullied' at Sporting Libson, according to reports. 

Ronaldo - who was born in February 1985 on the island of Madeira - felt 'lonely and homesick' while plying his trade at the Sporting Lisbon academy. 

Ronaldo struggled to fit in with the other kids after moving 535 miles away from his home town in 1997 at just 12 years old. Therefore, he was ecstatic to leave the club for United in 2003. 

However, things weren't always perfect for Ronaldo at United. The Portuguese superstar was involved in a training ground bust-up with Ruud van Nistelrooy shortly after he arrived and struggled to get the older players on his side. 

The information surrounding Ronaldo's difficulties at Sporting was revealed in a book called: Messi vs Ronaldo: One Rivalry, escortboy.online Two GOATs, and the Era That Remade the World's Game. 

In extracts published by , the book claimed that Ronaldo thought about hanging up his boots before his career had even started. He was planning to quit football while in the academy set up in Lisbon. 

According to the book, Ronaldo was teased for his heavy Madeiran accent by the other boys and cried every day because he missed his family and local friends.

Ronaldo struggled to control his emotions at such a young age and began lashing out as a result of his circumstances.

The young starlet was said to have been involved in a series of bust-ups and scrapes with other boys in the schoolyard. 

Additionally, Ronaldo is said to have thrown a chair at one of his teachers after they made fun of the way he spoke. 

As a result of his difficulties at school, Ronaldo was allowed to quit his studies and focus solely on football. He was called up to the Sporting first XI soon after. 

Speaking about his relationship with school, Ronaldo once said: 'I always felt that I wasn't cut out for school. So what was the point?'.

Despite dropping out of school and reaching Sporting's first XI, it wasn't until Ronaldo was sold to United for £12million that he started to fall in love with his career. 

This is because Sporting prevented Ronaldo from using the gym as he pleased. Therefore, he struggled to bulk up and found himself being knocked off the ball in games. 

Academy executive Aurelio Pereira once said: 'We never put children in gyms. That is one of the secrets behind our players' long careers. It's important to let them grow naturally.' 

Therefore, Ronaldo - who would tell his team-mates he would be 'the best in the world one day' - would reportedly sneak out of his dormitory at night to lift weights.

Ronaldo's night-time adventures didn't stay secret for long. Once the Sporting coaches found out, he was sentenced to detention. 

The club's hierarchy even locked the gym doors with a padlock to prevent the youngster from trying his luck again. 

However, this didn't stop Ronaldo from pursuing his goal of getting strong. He decided to get creative and use buckets of water in the shower to perform squats. 

Sporting's coaches intervened once again. They reportedly took the buckets away from Ronaldo. 

So, he began strapping weights to his ankles and racing cars in his free time to build up his explosive power. 

 Ronaldo was also caught using the cafeteria's oranges for keepy uppys after the coaches took their balls away from him to prevent him from overdoing training. 

When discussing Ronaldo's persistence, Sporting fitness coach Carlos Bruno said: 'He always wanted more. Most players, when the training goes on too long, they say, 'Hey, coach, too much water kills the plant, you know?' Cristiano was a guy who always wanted more water in the plant.'

However, things were also prefect at United for Ronaldo either. After joining the Red Devils as a relatively unknown teenager, Ronaldo was involved in an altercation with Van Nistelrooy. 

Speaking about the incident, Rio Ferdinand once said that Van Nistelrooy had gotten so fed up with Ronaldo's failure to provide a cross, he told the Portugal star he belonged 'in a circus'. 

Ferdinand said Van Nistelrooy's criticism of Ronaldo forge a desire within him to become one of the world's best. 

Following Van Nistelrooy's departure in 2006, Ronaldo went on to form a lethal partnership with Wayne Rooney.

They partnership helped fire the Red Devils to three straight Premier League titles as well as the Champions League in 2008. 

Gary Neville also admitted to moaning Ronaldo in his early days at Old Trafford because the young starlet was too 'erratic'. 

Neville vented to the club's strength and conditioning coach, Mike Clegg, as he was frustrated with Ronaldo's unpredictability. 

Speaking to Sky Sports at Ronaldo, Neville said: 'Sir Alex Ferguson and Carlos Queiroz, I think it's important to put Carlos Queiroz in the category with Sir Alex, they were both champions of him, they both believed in him.

'I think that he came back from the World Cup that summer it was like everything had changed. His maturity and his decision-making, which was a big thing, his experience, his physical attributes had completely changed overnight.

'He went from someone who, if you look at his early pictures at Manchester United, he was scrawny, really thin, wiry, didn't look very strong. 

'All of a sudden, I think it was after that 2006 World Cup, he came back like a super-middleweight boxer. His body had just completely transformed, he was absolutely incredible.

'From a strength point of view and a plyometric point of view, the ability to leap, the ability to score with his head, the ability to change direction, everything seems to fall into place. It was just a maturity, physically, mentally, everything happened to him.

'It was brilliant to watch, there was a point I remember going into the gym after one training session and speaking to Mike Clegg [United's strength and conditioning coach] who worked very hard with Cristiano physically in the gym and saying to him, 'I don't know what he's going to do next'. 

'You didn't know where he was going to be defensively, you didn't know when he was going to release the ball, players in the middle of the box didn't know when he was going to cross it. It was just erratic.

'But they had great faith in him, Sir Alex Ferguson and Carlos Queiroz, and they believed in him, put him forward in front of players who had greater reputations at the time and he developed into something brilliant.'