As a fan of the club, it was a career high-point, albeit an intimidating one. 'You're not late for Sir Alex,' he points out. 'Word went round that he was driving in, rather than walking, so we were jogging across the car park to make sure we were on time.
'[Sir Alex] said to me: "Welcome to the family,"' Nieboer adds. 'I thought that was a really interesting choice of words. No other club has done that.'
The 42-year-old Londoner reveals that his affection for the club dates back to 1991, when his father-in-law worked on the flotation of the club on the London Stock Exchange. 'It was great to just wander around Carrington [Man Utd's training facility],' he says. 'I remember the marble floors, the smell of Deep Heat and seeing all the players' boots on the shelves.'
Before becoming a marketer, a career in advertising took him from J Walter Thompson to WCRS. He has particularly fond memories of the former.
'I worked for Stephen Carter, or Lord Carter as he's now known. I learned more about standards and business thinking at JWT than anywhere,' says Nieboer. '[Carter] was ruthlessly intelligent. It was a grown-up place for grown-up brands.'
He left JWT for his first client-side role at Camelot, where he wrote a marketing and PR strategy that would play a key role in the company's successful bid to run the National Lottery.
Nieboer joined Betfair as a brand consultant in 2007, but was appointed global brand and marketing director shortly afterwards.
The past few months have been some of his busiest to date. High-profile activity around the 2009 Npower Ashes series included a series of novelty challenges between two former international cricketers, England's Phil Tufnell and Australia's Jason Gillespie, on which fans could place bets. Over the summer more than 92,000 visited the campaign website. They were also given the chance to participate in the final event of the series - a six-a-side cricket match.
That activity was followed by the sponsor-ship deal with Manchester United and another with European and Spanish champions, FC Barcelona. In dealing with the latter, Nieboer was struck by the club's emphasis on non-commercial priorities.
'My counter-part [in Barcelona] didn't ask about our marketing spend, but what we do from a CSR perspective,' he explains. 'The club is owned by the fans and its shirt sponsor is UNICEF, so getting the deal with Barcelona was a good measure of our brand.'
Matches between arch-rival teams, such as local derbies, present the best marketing opportunities for Bet-fair's 'Fan v Fan' pro-position, where it brokers bets between individual supporters. Later this month FC Barcelona and Real Madrid will meet in the highly charged El Clasico, and the online gambling company will be looking to take full advantage of its association with a team that symbolises Catalan pride, both in Spain and further afield.
Nieboer suggests there may be tie-ups with other football teams in the future, but, having snared two of world's biggest clubs, his priority is to consolidate Betfair's position. 'We are having one or two conversations with other clubs, but we want to do these deals properly first,' he says.
The Betfair marketing strategy centres on engaging directly with supporters. Activity around September's Manchester derby included a life-sized table football game, while posters promoting betting on United's game against Liverpool last month included copy written by fans. 'Some of the posters were covered in graffiti; we were quite happy about that,' says Nieboer.
Betfair has had ties with several sports over the years and, while this will continue, the brand's association with football will lead its customer acquisition strategy.
As part of a campaign that broke in September, TV ads are shot each week at the company's headquarters, in a mocked-up 'Fan living room', along the corridor from Nieboer's office. This activity features five Premier League football fans discussing the hot topics of the week. Three hours of heated debate is edited down to just 30 seconds of footage for each ad. Nieboer gives the impression that he would enjoy nothing more than taking part himself.
The 2010 FIFA World Cup may be in the company's sights, but the event is not as central to Betfair's marketing plans as one might imagine.
'We see it as a stepping stone between the end of the [domestic] season and the next one,' says Nieboer, explaining that the 'Fan living room' brand activity will be adapted for the tournament.
'The marketing plans for the World Cup are not yet fully formed as the tournament is still some way off,' he adds. 'It will be the first major tournament for England for four years, so it's a massive opportunity, but we don't want to overcook it. It's only a six-week tournament and we are in football, day in, day out. In the past, we've got obsessed with one or two key events.'
Nieboer has been based in Hammer-smith for nearly five years - first as managing director of Virgin Games, and now with Betfair. While the short commute to work from his home in West London, and the modern offices on the bank of the Thames, have their appeal, he says he is less than enamoured with the area.
Luckily, he has a weekend escape in Norfolk, where he lives with his wife and two sons. 'I'm not a country squire, although maybe some people around here think I am,' he says. He does, however, profess to be a 'handy shot', having taken up shooting when he was just 16. He bags pigeons and pheasants and also enjoys game fishing.
Location aside, Nieboer is clearly enjoying life at Betfair and cannot resist a cheeky swipe at traditional betting companies, saying: 'We are the only bookmaker that wants England to win.'
Having spent his first two years in the company targeting the early adopters, Nieboer is now going after a group he refers to as the 'early majority'.
He plans to reach this audience through marketing strategies that educate the consumer about Betfair's unique positioning, pitting fan against fan, rather than punter against bookie.
- 1992-98: Various roles, rising to board director, J Walter Thompson
- 1998-2000: Board director, WCRS
- 2000-02: Marketing director, Camelot
- 2002-04: Vice-president marketing, MGM Mirage Online
- 2004-07: Managing director, Virgin Games
- June 2007-present: Global brand and marketing director, Betfair
- Lives: Norfolk and London
- Family: Married with two children
- Hobbies: Shooting, fishing, cricket, football