Last week's 1-1 draw between Manchester United and Real Madrid was "the match the world wants to see", according to the Spanish team's coach, Jose Mourinho. In fact, Manchester United claim any of their matches is of interest to one in 10 of the world's seven billion people. What is the evidence for this claim?
Even the most ardent opponent of Manchester United would acknowledge that the club has fans right around the world. But the statement that it has a global following of 659 million adults - out of a total five billion adults in the world - is still quite staggering.
This is not just a number picked out of thin air, though. Manchester United used a market research company, Kantar, to carry out a worldwide survey.
The company polled nearly 54,000 adults in 39 countries between June and August 2011. Some were surveyed face to face, but most answered questions online.
It then extrapolated from these survey results to produce a figure for each of those 39 countries - and for the rest of the world - taking into account such things as the popularity of football in these countries, and whether players born in them had played for Manchester United in the past.
Of the 659 million figure, Kantar says roughly half (325 million) live in the Asia Pacific region, 173 million in the Middle East and Africa, 90 million in Europe and 71 million in the Americas.
"I would back my figures and argue [they are accurate] to within a 1% margin of error," says Kantar director Richard Brinkman.
"We work for a number of the largest companies around the world… it's in our interest to use our knowledge to produce an accurate figure, not the biggest figure. We need to have more credibility than that."
But there are plenty of football pundits who responded sceptically to the announcement of the figures in May 2012.
"The idea that Manchester United have 108 million followers or fans in China alone for example - which is what this research purportedly showed - is patently ludicrous," says Nick Harris, editor of sports finance website SportingIntelligence.com.
He also draws attention to the contrast between this survey, and one published in 2007.
"In five years, purportedly, Manchester United's following has gone from 333 million, or thereabouts, to 659 million. So almost a doubling of people following Manchester United in five years. This is eyebrow-raising stuff!"
Nick's eyebrows were also raised by Kantar's suggestion that more than 30% of South Korea's total population of 49 million were followers of Manchester United.
Live viewing figures for Manchester United matches in the country come in at less than one million people. And even taking the time difference into account, Nick questions just how much following these "followers" are doing.
It's important to understand this word "follower", because it is "followers" that Kantar set out to count - not "fans".
Kantar included in this category people who answered, unprompted, that Manchester United were either their favourite football team or a team that they enjoyed following.
So there is nothing to stop people "following" several clubs, as Kantar director Richard Brinkman acknowledges.
"They will follow more than one club," he says. "Indeed, that's a trend we're seeing around the world, particularly in developing markets. People do follow more than one club."
But on the face of it, you might think the number of fans a clubs has is more interesting than the number of its followers. So why was Manchester United so keen to get a figure for its followers?
It's partly to do with sponsorship, explains marketing consultant Ben Wells.
"Every sponsor... will expect a rights-holder to bring with them a number which correlates their potential reach," says Wells, who spent six years as head of marketing for Chelsea.
During his time there the club did release one figure relating to the numbers of fans worldwide - about 110 million - though Ben admits he is sceptical about the significance of such figures.
"A lot of people get wrapped up in huge numbers," he says.
It's unlikely to be a coincidence that Manchester United made the figure public shortly before the club's Initial Public Offering (IPO) on the New York Stock Exchange, and featured it in the pitch to potential investors.
"Through our 134-year heritage we have won 60 trophies, enabling us to develop what we believe is one of the world's leading brands and a global community of 659 million followers," the document said.
Nick Harris says he can understand the motivation for trying to get this figure across.
"Soccer is not a massive mainstream sport in America. American sports can be quite insular. [American] sports fans think that the NBA basketball the NFL [American football] and MLB baseball are global sports, but of course they're not," he says.
"They're primarily American sports with American audiences. They perhaps don't realise that football is the only truly global game. Manchester United wanted to ram home quite how global football is."
Which brings us to that favourite adage of Manchester United's opponents - that most of the club's fans do not come from Manchester at all.
In fact, if you believe the team's own figure, a tiny proportion of followers - fewer than 0.1% - come from the city.