Portugal coach Carlos Queiroz says the work ethic of Real Madrid star Cristiano Ronaldo comes from his former Manchester United teammates.
He told the Daily Mail: "I think he learned at Manchester United from players like Roy Keane, Paul Scholes and Ryan Giggs, because they all had that winning mentality and a determination to work hard.
"With Cristiano's nature in that environment, he grew up overnight. It was a factory like no other in football."