David Beckham has one leg longer than the other, the England captain told the News of the World on Sunday.
Beckham said he was unaware of the problem until he underwent a medical before his transfer from Manchester United to Real Madrid last July.
"One of my legs is shorter than the other," he told the newspaper.
"I think it's a common problem but the difference in mine is a bit more unusual."
"I didn't know about it until I signed for Real and it showed up in the medical."
"The doctors told me: 'By the way, you've got a little bit of a problem with your back.' Thankfully, it's not a big problem," said
Beckham.
The midfielder has been troubled by a string of injuries since joining Real. He has missed the last three games because of a problem with his right ankle but is back in the squad for the away league match against Real Betis later on Sunday.
"My left leg is shorter than my right," he said.
"I have tried to wear insoles to help but I can't wear anything in my (soccer) boots."
"That's the problem with my present injury," he said.
"I don't like wearing anything padded because I only want to feel the boot against my foot and nothing else, especially when I'm taking free kicks."