It started with his dad, and Ted Beckham can still be seen now on European trips, cheering on his beloved Red Devils. The obsession was passed to his son, despite their Leytonstone roots.
It explains how David Beckham ended up at one of Bobby Charlton's soccer schools, it explains why there was never a chance of Beckham ending up at Orient, or Tottenham, or any other London club that was far more local than Old Trafford. It explains why Beckham was in tears when he learned the Champions League first knockout round would provide him with a chance, after seven years, to say goodbye.
"Leaving United was the toughest thing I had to deal with in my whole career," he reflected in a recent interview. "Coming to terms with not being a United player was very hard. When you are a Manchester United fan and a Manchester United player, you never want to play for anyone else."
It was always that way for Beckham. When he emerged from that famed Youth Cup-winning 'Class of 92' all he wanted to do was make a first-team appearance. When he did that - scoring the kind of free-kick that was to become his trademark against Galatasaray in 1994 - he wanted to win something, win something else, play well enough to lead his country, become a national icon. Tick, tick, tick, tick.
Hitting high notes
Beckham's triumphs with United are part of club legend. Although he was the first of that amazing group of youngsters to leave Old Trafford, he left an indelible mark: Six titles, a couple of FA Cups. A Champions League. The treble.
There is no doubt Beckham will be afforded a hero's welcome on Wednesday. The supporters who travelled to Milan three weeks ago bellowed their approval from the top tier of the San Siro. Old Trafford is going to be a pretty noisy place when Becks makes his entrance.
For all the irritation he caused Ferguson towards the end of his United career - the Scot felt fame itself had become a monster controlling Beckham, with his wife Victoria guiding him into the showbiz stratosphere - he remained a fans' favourite.
While old friend Ryan Giggs was criticised by United fans when he did not play well, Beckham's more robust approach, often charging around doing nothing but barging opponents when things were not going his way, appealed to the sense of industry demanded.
It is a two-way thing of course, which is why Beckham previously viewed a return with trepidation. "United were the club I always wanted to play for and I loved every minute of my time there," he said. "The thought of playing against them for Real Madrid always gave me that sick feeling because I just missed the club so much."
Leaving home
That trepidation was also partly down to the way Beckham left. His final game might have been at Everton, when another of those wonderful free-kicks put the Red Devils on the road to the title, but the season is remembered for two other events; the boot Ferguson lashed out at after an FA Cup defeat to Arsenal that struck Beckham just above the eye, and the two goals he scored in defeat against Real Madrid after he had been left on the bench.
There was a wound with the man he called "boss" that was not properly healed until 12 months ago, when Beckham and Ferguson enjoyed a public reunion in the San Siro ahead of United's encounter with Inter Milan. It brought a sense of calm, and left Beckham feeling the time was right for a proper meeting.
Ferguson was quite happy with part one, Beckham less so. He has some work to do if he is to emerge triumphant. And what of Ted Beckham. Son or club? Son does not want to ask. "I have not asked my dad who he wants to win," Beckham said. "I don't think he would tell me the truth anyway."
Beckham's memorable moments at the 'Theatre of Dreams'
15 May 1992 - Beckham is part of the famous 'Class of 92' who complete a two-legged Youth Cup final triumph over Crystal Palace alongside Gary Neville, Nicky Butt, Robbie Savage, Keith Gillespie and Ryan Giggs.
7 December 1994 - His first United goal, typically a free-kick, in the Champions League against Galatasaray. It was the first of 84 in total for the Red Devils.
28 April 1996 - Scores twice in a five goal demolition of Nottingham Forest towards the end of a season in which he finishes as a Premier League champion for the first time
16 May 1999 - The first leg of the Treble. At home to Tottenham, needing a win to secure the title. Spurs led, but Beckham had his own plans and duly scored the equaliser. Andy Cole got the winner and the championship was won on home soil.
1 April 2000 - Contributes to United's 7-1 hammering of West Ham, It forms part of a run of six goals in 10 games from Beckham as United cruise to the title.
6 October 2001 - By now the England captain, Beckham was part of a team that only needed a point against Greece to secure a place at the World Cup. Trailing as they headed into injury time, Beckham kept his cool and curled home a glorious free-kick to send a nation into jubilation.
10 April 2002 - The English public were largely unaware of what a metatarsal was until Deportivo's Aldo Duscher broke the second bone in Beckham's left foot during a Champions League quarter-final. Beckham was ruled out for the season and England awaited news of his recovery. He did make the World Cup but his performances were poor.
15 February 2003 - Beckham is left sporting an ugly gash above his left eye after finding himself on the receiving end of a stray boot kicked by an enraged Sir Alex Ferguson following an FA Cup defeat by Arsenal.
23 April 2003 - Being dumped on the bench for a Champions League quarter-final decider effectively ended Beckham's United career. He went with a bang, though, scoring twice in a 4-3 win.
3 May 2003 - Scores the opener as United beat Charlton 4-0 to set themselves up for another title win at Everton the following week. Beckham has not played a club game at Old Trafford since.
