David Beckham faces a near-impossible task to turn football into one of the USA's major sports, according to Sir Alex Ferguson.
The Manchester United manager feels his former Old Trafford protege cannot transform the fortunes of the sport by himself.
And he argued the sheer size of the USA and the exodus of young American talent to Europe would stunt the growth of Major League Soccer despite Beckham's best efforts.
Ferguson also claimed the former Real Madrid player's celebrity status had overshadowed his significance as a footballer.
Los Angeles Galaxy signed Beckham - currently out with a knee injury - on a five-year contract worth up to £128million in a bid to boost the popularity of the game. But Ferguson feels the England midfielder will struggle to have a major impact on his own when the combined talents of Pele, Johan Cruyff and Franz Beckenbauer failed to have a lasting impact after playing for New York Cosmos three decades ago.
'In the late `70s I went to America with Aberdeen and there were guys like (Teofilo) Cubillas and (Peter) Shilton there,' the Scot said.
'Before that there was Pele, Cruyff, Beckenbauer. It is difficult with David going there - I don't know what kind of impact he can make. David Beckham himself can't change the whole country.'
And Ferguson feels the distance between teams affects the impact of football on American society.
'The size of the country makes it difficult,' he said.
'In European football, and especially in British football, you can travel easily. 'If you are Boston and need to go to Los Angeles it's a six-hour flight. Supporters don't travel so you are missing that rivalry between fans.
'So you have a problem. To make it substantial you would have to go regional but there's not enough teams to have four strong leagues.'
Ferguson, who was speaking to an audience at the Citizens Theatre in Glasgow, feels the MLS is also undermined by an exodus of young homegrown talent.
'What you have got in the States is that a lot of kids are playing football in the States and there is nowhere to go,' he said.
'The best American players go to Europe very early, like Brad Friedel (at Blackburn), (Brian) McBride and (Clint) Dempsey at Fulham. So that situation doesn't help the American game.'
And while Ferguson feels Beckham will struggle to have the required impact on the field, he claimed the 31-year-old's celebrity persona had overtaken his status as a sportsman following his marriage to Spice Girl Victoria.
When asked if Beckham was difficult to deal with at United, the 65-year-old said: 'He was never a problem until he got married. He used to go into work with the academy coaches at night time, he was a fantastic young lad.
'Getting married into that entertainment scene was a difficult thing - from that moment his life was never going to be the same.
'He is such a big celebrity, football is only a small part. The big part is his persona.'