Strolling down New York's Fifth Avenue, his hands full of summer shopping, Romelu Lukaku took the first of several phone calls that would ultimately change his life.

'It was Jose Mourinho,' grins Lukaku's childhood friend Vinnie Frans. 'It was the final week of June and we were in New York. He was on the phone saying "Yes, boss", "OK, boss" so I knew it was Mourinho.'

For Manchester United, one phone call would not be enough. Mourinho's first call was part of a dramatic hijack operation that disorientated Chelsea and led to Lukaku becoming the club-record £75million striker entrusted to fill the goalscoring vacancy left by Wayne Rooney and Zlatan Ibrahimovic.

Romelu Lukaku completed a £75million move to Manchester United from Everton this summer

But it could have been very different, with Chelsea keen on securing his services

Lukaku with mum Adolphine and dad Roger, who himself is a former football player

The Belgian striker (circled), playing with his school football team at a tournament in 2006

Lukaku often towered over opponents in his youth and carried his passport to prove his age

Everybody expected Lukaku to return to Stamford Bridge, at the club that began scouting the Belgian when he was only 12-years-old. Chelsea subsequently bought Lukaku aged 18 and then Jose Mourinho sold him at the age of 21.

Yet Frans, who was with Lukaku and Paul Pogba in Los Angeles as the transfer dramatically took shape, explains that United simply wanted the player more.

'As a child, it was all about Didier Drogba. When he scored goals on the street, it was the Drogba celebration with the arms. But he just had one call from Antonio Conte. Manchester United came with three different contract offers and Chelsea did not present one. United wanted him more and that's the reason he chose them. Rom had it clear that he wanted to start pre-season properly with a new team. Chelsea kept waiting and waiting so he thought "United have come with a good offer, Mourinho has great ideas and he was 100 per cent sure Mourinho wanted him".

'At first he was like "Let me wait a bit and see what other clubs are doing". But United wouldn't take no for an answer. After the second offer he thought "Hmmm, they really want me". Then it was a third time and it was "Hmmm with a few 'M's" then the fourth came and it was "OK, I'm going to Manchester". Pogba was talking up United but it was always going to be Romelu's own decision.'

But Jose Mourinho hijacked the deal, contacting Lukaku again and again to secure the transfer

Chelsea manager Antonio Conte only contacted the Belgian forward on one occasion

LUKAKU'S CAREER 2008-11: Anderlecht - 73 games/33 goals 2011-14: Chelsea - 10/0 2012-13: West Brom (loan) - 35/17 2013-14: Everton (loan) - 31/15 2014-17: Everton - 110/53 2017-: Manchester United * league games only Advertisement

'In LA, Jose called him up again and said "Have you made a decision?" He said "Boss, I'm coming to United".'

Back to reality and Frans was this week back home on the council estate of Wintam, a small village about 20km north of Brussels. Duiventilstraad 71 represented a humble abode for the Lukaku family.

Romelu lived with his brother Jordan, who plays for Lazio, along with mother Adolphine and father Roger, an ex-footballer in Belgium who grew up in the former Zaire, now the Democratic Republic of the Congo. Speaking over the past week to former friends and mentors of Lukaku, a picture emerges of a family that strived against a backdrop of financial struggle and inequality.

Adolphine worked as a cleaner while Roger's career did not provide financial security for the family. At SJABI school, general director Ivo Marnef recalls how the school supported Lukaku. 'His parents weren't so rich. His dad sent money home for his family in Congo. It was very difficult for them. Financially, we helped them at school. It was not easy to pay the bills. Romelu kept missing the bus to school, so I gave him a bike to cycle to school. I gave the dad a job as a trainer at a youth club - a tiny wage.'

Lukaku did not find the net during his time with Chelsea and spent spells out on loan

The move to Old Trafford means Lukaku is reunited with former Chelsea boss Jose Mourinho

At his local youth clubs, Lukaku made an instant impression. His first coach, Erwin Wosky, recalls 'a powerhouse that was taller, stronger and more determined than everyone else'. He adds: 'Even at the age of nine, he already had an adult size eight shoe. He would use size five balls whereas other kids used sizes three or four.'

At KFC Wintam, coach Steve De Buyser took Lukaku under his wing, correcting defects in his game.

'He had a brilliant left foot but we wanted his right to be stronger. So we took his left boot off him and made him play with one shoe in training. Now he has two brilliant feet.

'I remember one tournament in France. His boots were shattered and worn out. I bought him new ones and he was player of the tournament. At 16, he signed his contract with Anderlecht and the first thing he did was call me and give me complete access to Anderlecht for a year as a thank you.'

He played regularly at West Brom, where he scored 17 goals during his time at The Hawthorns

He then moved to Everton, initially on loan, before making a permanent switch to Goodison

By age nine, Lukaku was scoring goals at a jaw-dropping rate. In one season, including tournaments, he scored 186 goals despite playing against boys two years older than him.

De Buyser adds: 'Coaches didn't believe he was so young. He had to carry his passport everywhere to prove it. Other kids saw him coming on the field and they started to literally cry. He was a beast.'

At the age of 14, Anderlecht signed Lukaku. He continued to live at home and the Belgian club would organise a minibus to ferry him to and from training. He made his debut at age 16 and scored 33 goals in 73 games before Chelsea came calling when he turned 18.

Former Chelsea sporting director Frank Arnesen explains the work that went into the signing, with Manchester United and Juventus also monitoring him. Chelsea's background work was methodical, receiving films of Anderlecht youth games while Drogba himself made direct overtures to Lukaku.

Arnesen said: 'When he was 12 or 13 years old, my son Sebastien watched him.

'His attitude was everything. He was already a star at 16. He was at school in Anderlecht and the teachers told us there was no arrogance and there was no "I'm a big shot" act.

Pictured during his time at Anderlecht, where he scored 33 goals in 73 appearances

The young Lukaku was a teenage sensation who attracted attention from across Europe

'When I was there, we more or less had an agreement for a £2million deal about a year before Chelsea signed him. Chelsea hesitated as it was more money than they were used to paying for a young player. Roman thought it was too much. I left and a year later he signed him for £10m more. But that's the way it is sometimes.'

At Chelsea, Lukaku had to bide his time, making a loan move to West Brom, where he scored 17 Premier League goals. Then he joined Roberto Martinez on loan at Everton.

Martinez, now his coach for the Belgian national team, tells Sportsmail: 'We knew we were taking on potential. He had only played seven full 90 minutes in the Premier League for West Brom. We had to get him playing full games. I remember one game against Newcastle for us live on TV and you could see from 70 minutes he was almost out of breath.'

After 15 Premier League goals, Martinez committed £28m to his permanent signing and the judgement on potential has paid off. 'He has never lost his key strength, he is a stunning finisher. His goalscoring threat with his left foot is what separates him. I had previously sent my chief scout Kevin Reeves at Wigan to watch him at Anderlecht.

A cutting from a newspaper in Belgium shows four-year-old Lukaku eating ice cream

Lukaku gives Everton the lead. Let's take a moment to remember that photo of him playing for Anderlecht's youth team: pic.twitter.com/HFgiVCXjjG — Ian King (@twoht) August 15, 2015

'His workrate is amazing. He is determined to sharpen up what he is already outstanding at. There were times I'd have to drag him off the training ground. He would take a sack of balls and practise finishing or running with the ball and shooting. Some players don't work at what they are already good at. He does not get bored in the quest for perfection.'

At Anderlecht, they speak with similar enthusiasm, with coach Rene Peeters explaining how Lukaku would demand extra one-on-one training to improve his first touch.

The club also ensured he followed through his education. Lukaku speaks six languages with fluency and has a high school degree in public relations.

In fact, Anderlecht press officer David Steegen recalls giving Lukaku a book of Mourinho quotes after a trip to England when he was a teenager.

Lukaku has not forgotten his roots. Earlier this year, he visited Anderlecht and addressed youth players.

Lukaku has already scored twice for United during his first three pre-season outings

Lukaku's first football registration card for youth team KFC Wintam

When his first coach, Erwin Worsky turned up to Belgium training, Lukaku gave him a tour of the changing room. He sometimes returns to hometown Wintam to visit Vinnie - albeit in either his Bentley Continental or Rolls Royce Phantom.

His mother remains the dominant influence. Martinez recalls Adolphine visiting Everton training. 'When she was around, you would see a bigger smile on his face. She came to the training ground and you could feel his pride, to show her what he was achieving.'

His best friend Frans adds: 'They are fighters. His mum would come to us and say "Can you lend us ten bucks?" and we would do that. A few days later, she would always return it, even when they had so little. We had a close bond as families.

'She is delighted with the transfer. He has huge confidence in Mourinho. There are no hard feelings because Jose sold him previously.

'If he really wanted revenge on Mourinho, he'd go to Chelsea. It's not only the manager who sends you away, it's the whole club. He always said to me "Vinnie, Mourinho is one of the best coaches in the world, I really want to work with Mourinho".

'He tells me "I do it for my mum and God and nobody else". Nobody is gonna stop him.'