David Beckham thought he was too big for Manchester United and later surrendered part of his career by moving to the United States to play for the Los Angeles Galaxy, former manager Alex Ferguson said in his autobiography, published on Tuesday.

Beckham, who burst into the limelight after coming through the ranks at United, features heavily in My Autobiography, published by Hodder and Stoughton, Ferguson's recollections of the years since the 1999 treble-winning season.

Ferguson's relationships with former skipper Roy Keane, current striker Wayne Rooney and arch-managerial rivals such as Rafa Benitez and Arsene Wenger also get plenty of wordage.

Ferguson, 71, ended 27 years in charge of one of the world's biggest soccer clubs last season after winning a 13th Premier League title for the club.

During a time of huge change in the soccer landscape, the one constant to emerge was Ferguson's vice-like grip on authority in the face of the big egos and even bigger salaries of those under his command.

He was regularly challenged but invariably emerged on top.

Beckham is a prime example, his relationship with Ferguson damaged irrecoverably after an FA Cup defeat by Arsenal in 2003 after which Ferguson kicked a boot at Beckham after he was "dismissive of my criticism".

Ferguson said instead of "becoming a United legend" Beckham allowed his love of celebrity to get in the way.

"David was the only player I managed who chose to be famous, who made it his mission to be known outside the game," Ferguson wrote in a chapter devoted to Beckham. "I felt uncomfortable with the celebrity aspect of his life."

After the boot incident - which left the player with a cut forehead - Ferguson told the United board "Beckham had to go."

"The minute a Manchester United player thought he was bigger than the manager he had to go," Ferguson said.

"David thought he was bigger than Alex Ferguson. It doesn't matter whether it's Alex Ferguson or Pete the Plumber. The authority is what counts.

"You cannot have a player taking over the dressing room. That was the death knell for him."

Beckham, who won six league titles with United, was sold to Real Madrid soon after and eventually joined LA Galaxy in 2007 - a move that baffled Ferguson.

"There was no footballing reason for him to go to America," Ferguson said. "He started making decisions that rendered it hard for him to develop into a really great footballer.

"I would look at him and think, "What are you doing, son?"

Ferguson also saw off former skipper Keane after the tempestuous Irishman lambasted his teammates on the club's TV channel in 2005.

"The hardest past of Roy's body is his tongue," Ferguson wrote. "What I noticed that day as I was arguing with him was his eyes narrowed to black beads.

"It was frightening to watch. And I'm from Glasgow. What you did in that video was a disgrace," Ferguson recalls of his reaction to Keane's outburst.