Former world number one Andy Roddick believes that the days when tennis players won Grand Slam events when in their teens are over and that Andy Murray has shown years of hard work, graft and determination are what is needed to win one of the sport’s biggest prizes.

Roddick retired from the game back in September, shortly after his 30th birthday and he believes that the fitness and talent of the top four players in the world is too much for someone like him to compete with.

He said: “Boris Becker won when he was 17, Rafa (Nadal) won when he was 19, I won when I was 21 and now there is not a teenager in the top 100 at the moment because you aren't strong enough at that point in your career."

There are not many players in the sport that work harder than Murray as he is known to spend a lot of the off-season, even Christmas Day doing intense training to make sure he remains in shape for when he is back in action again.

Roddick, who was the last American to win a Grand Slam back in 2003, is a big admirer of the way that the Scotsman goes about his business.

"He gets it. He gets what it takes. It just seems that over the years he became more and more motivated, perhaps because of the pressures that were put on him, he almost took it the other way and ratcheted it up and worked harder, that is something you respect." he added.

The 30-year-old now believes that Murray will go on to have a superb few years in tennis and thinks it is between now and when he turns 30 where he will win the majority of his titles. Even if you prefer playing Pub Games, you will know that the first Grand Slam win is the toughest.

Roddick also insisted that he did not fall out of love with the game, but his body could simply not cope with the gruelling ATP schedule: "I've never really resented the game, I've always loved it and enjoyed it just my body wouldn't let me do it at the level I was accustomed to and I didn't want to do it at a lower level than I was used to."