Marriage to Posh changed Becks for the worse, claims Fergie

The Manchester United boss also said that the LA Galaxy midfielder will struggle to make an impact on the game in the United States.

Beckham will miss England's vital two Euro qualifying matches with Israel and Russia with knee injury, and the fresh assault from his former manager will not help his recovery process.

Ferguson claimed the 31-year-old's celebrity persona overtook his status as a sportsman following his marriage to Spice Girl Victoria right) just after United won their momentous Treble.

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."

The fresh attack mirrored the one Ferguson launched in 2003 in US magazine Sports Illustrated.

Then he said: "He [Beckham] was blessed with great stamina, the best of all the players I've had here. After training, he'd always be practising, practising, practising. But his life changed when met his wife.

"She's in pop and David got another image. He's developed this 'fashion thing'. I saw his transition to a different person."

Ferguson also believes that his former midfielder faces a near-impossible task to turn football into one of the major sports in the US.

Los Angeles Galaxy signed Beckham 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 1970s I went to America with Aberdeen and there were guys like (Teofilo) Cubillas and (Peter) Shilton there," the Scot insisted.

"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."

Ferguson also 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 in Boston and need to go to Los Angeles it's a six-hour flight. Supporters don't travel, thus 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 there but then 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."