Former Manchester United manager Sir Alex Ferguson says Cristiano Ronaldo was the greatest trainer he worked with.

Fergie made the revelation as he spoke as a guest at 'An Evening with Rory McIlroy' in Dublin.

“During my time at Manchester United I was lucky enough to have a lot of people who put in countless extra hours to get better.

"Gary Neville turned himself from an average footballer into a wonderful one because of his work ethic, as did David Beckham. But Ronaldo used to completely exhaust himself, and still does.

"He just wanted to be the best in the world."