Manchester United have released research which claims that nearly one person in 10 across the globe supports the Red Devils.
United have announced new research showing they have doubled their number of worldwide fans over the last five years.
The survey, conducted on behalf of the club, said they have an estimated 659million followers worldwide - nearly a 10th of the seven billion global population.
Their nearest rivals are Barcelona but United enjoy twice the support in Asia, seen as the key market for the future, as the Catalan giants according to the survey.
Market research firm Kantar gathered responses from 54,000 people across 39 countries online and face to face, and asked interviewees which "team or teams they followed" - more than one club could be named.
Richard Arnold, the club's commercial director, said the depth of support had helped United's commercial income soar - it has risen by at least 10 per cent every year since 2007.
"Our family of followers has doubled in five years and across the world this represents a very, very important asset and relationship for the club," said Arnold.
He added that 88 per cent of United's support was in emerging markets which are seen as the most important areas for potential growth, including 108million fans in China, 55million in Indonesia, 35million in India and 26million in Vietnam.
North and central America is also a growing area for fans, with 24million in Mexico and 34million in North America.
The research was carried out between June and August last year, after United had won the Premier League and reached the UEFA Champions League final, but Arnold rejected suggestions that the club's relatively unsuccessful season this year would have led to any significant drop in global support.
"It is one of the huge myths that fans are fickle," he said.
"Research by Barclays globally showed that 85% never change the team they support - think of that in terms of the divorce rate. It changes less often than who you are married to.
"If you have been to China or New York and seen the Beatles effect at airports and hotels then it becomes very easy to appreciate the way people feel."
Arnold said the support had contributed to United's commercial success - their training kit sponsored by DHL is now the fourth-highest selling kit worldwide, while 10,000 United branded Honda motorcycles that went on sale in Thailand sold out in two weeks.
United's groundbreaking 13-year sponsorship deal with Nike that was done in 2002 expires in 2015 and Arnold said it was unlikely for such a long-term deal to be done again, especially given the pace of technological developments.
"Five years ago no one had a tablet [such as an ipad]. Five years is forever," he said.
United are carrying out major improvements to their Carrington training ground but Arnold said there was no intention to try to sell naming rights for the development.