The celebrity superstar, 28, joined Real for 25 million pounds on July 2 after United, whom he had joined as a fresh-faced schoolboy, had originally accepted a similar bid from Barcelona.

Beckham's four-year contract with the nine-times European champions is worth an estimated six million euros a year before bonuses.

But despite the frills of playing with one of the biggest clubs in the world, Beckham admitted in an ITV documentary he was stunned to learn that United had accepted an offer for him in the first place.

"I didn't think for one moment it would happen.

"I was more upset than anything because I had put so much into the club. I felt I had given 120 percent every time I performed," Beckham said in the documentary entitled The Real Beckhams.

Beckham also revealed his regret that he and Sir Alex Ferguson have hardly spoken since he left the club.

"He hasn't spoken to me still," said Beckham. "We spoke for five minutes at a funeral. He hasn't rung me ... I really would have thought that would have happened to be honest.

"I just expected a bit more respect when I had been at the club for that many years."

Beckham admitted that his move to Spain, along with wife Victoria and sons Brooklyn and Romeo, had been stressful.

"Things have been difficult moving to Spain," he said. "It's just been very difficult and it has been very stressful."

But he added: "I think we've come out of it alright.... We've got over a lot worse than this."