Former world number one Andy Roddick believes the days when players captured grand slam titles in their teens are over and that Britain's Andy Murray has shown that years of hard graft need to be put in to achieve success in the modern era.
Roddick, who retired from the sport in September shortly after his 30th birthday, believes that the current generation's supreme fitness has made it hard for players to compete in their thirties and this has also made winning a slam young almost impossible.
"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," said Roddick, the last American man to win a slam at the 2003 US Open.
"The game has got more physical and the schedule has got longer. It's a really difficult sport physically and mentally," he said.
Murray is known to spend the off season, including Christmas Day, doing hours of intense training in the Miami heat and Roddick said he was delighted to see the Scotsman's hard work finally pay off when he won his first slam at the age of 25 at this year's US Open.
"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," Roddick said.
"I don't think you could have known that about him when he was 19-years-old. He has taken his lumps, every defeat for him got magnified and to see him break through... I was really truly happy to see him have his success.
"One little secret of the guys who have won one slam, is that we don't want other guys to win one because its like a bit of a special fraternity. But I was cheering for Andy to break through. He is too good a player not to.
"He definitely has all the talent to parlay this summer into a three or four year stretch, there is no reason why he can't".
It is no coincidence that Roddick sees a run of Murray wins running until the Scotsman is heading close to 30 - the age when he says his own body could not cope with the intensive schedule of the modern tour.
OUT OF LOVE
The three-times Wimbledon runner-up says it was not a case of him falling out of love with the game - just with the gruelling demands of the ATP Tour.
"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," he said.
The American will be back on court for an exhibition tournament, the Miami Tennis Cup, on November 30. While he will be up against the likes of Murray and Spain's recently retired Juan Carlos Ferrero, Roddick says he is not tempted by other opportunities to play regularly.
"I don't have much interest in being on a senior tour. I don't think I retired so that I could be on tour. I like playing tennis, I've always enjoyed the process of being a tennis player, I'm just not sure that I enjoyed the travel at the end and my body didn't recover from the day-to-day grind," he said.
Roddick has certainly eased off though since retiring from the tour, enjoying previously off-limits activities such as mountain biking but conceding that his diet has been "average at the best".
"There is a difference between working out and training and I've definitely been working out and not training," he said.
Many imagined that Roddick, a confident communicator, could be a successful television commentator but for the moment that role does not appeal to him.
"If I'm being honest I think I'd be good at television, I just don't know if I am interested because you are kind of geographically responsible to a location and frankly I don't know if I retired from tennis so that I could sit around tennis tournaments 12 hours a day. It's not something that really interests me right now.
Roddick is no hurry to set a pattern to the next years of his life - he has his foundation to help under-privileged kids to keep him busy and is enjoying more time with his wife, model and actress Brooklyn Decker.
While he clearly would have loved to turn one of his Wimbledon finals into a second grand slam title, he is not spending his free hours looking back with regrets.
"As far as how I went about day-to-day business, I'm pretty proud of it. I don't think I left much on the table - I don't know that I was blessed with the artistic ability of Roger (Federer), or the physical ability of Rafa, or the options that Andy Murray has, but I feel that a got a lot out of what I was given," he said.
"I look back and feel very comfortable with what I was able to put into the game."