Manchester United legend Ryan Giggs has heaped praise on former teammate Cristiano Ronaldo for managing to stay at top of his game for so long.

Ronaldo has won four of the last five Ballon d'Or titles and at the age of 33 has scored 28 goals in 31 appearances across all competitions this season, including 11 in just seven Champions League outings.

Giggs himself played until the age of 40, and he believes that the longevity of the likes of Ronaldo and 20-time tennis Grand Slam champion Roger Federer - both of whom were nominated for the Laureus Sportsman of the Year award - are particularly impressive.

"I'm a sports fan and I think when you watch people at the top of their sport, someone like Cristiano Ronaldo, someone like Roger Federer, who may be coming to the end of their career and they have question marks on them and they still are the best at their sport, they're people who stand out for me and they're people you can admire," Giggs told Sports Mole.

"It is hard, because when you get to late 20s, early 30s, if you have a bad game or you don't produce the form you did when you were younger, you get questioned.

"'Is he finished?' Or 'is he too old?' Of course if you look after yourself - I think Cristiano and Roger Federer are proof of that - you can go on into your 30s."

Giggs was last month appointed Wales manager, and will take charge of his first game as national team boss against China on March 22.