Andy Murray is "stuck playing defensive tennis" and needs to "change his mentality" to win grand slams.

That is the verdict of top coach Larry Stefanki, the man behind former world number one Andy Roddick, who ended Murray's dreams of Wimbledon glory on Friday. Murray was a hot favourite to beat Roddick in the semi-finals and become the first British man to reach the Wimbledon final since 1938, but lost in four sets to the inspired American.

"I think the difference was that Murray's second serve was very attackable. That was the plan, to move in and club some second serve returns," Stefanki said in an interview with Radio Wimbledon.

"I don't think Murray transitions to offence well enough. He is stuck playing defensive tennis only and, in my opinion, that was the big difference. I don't think Murray played enough offence yesterday.

"Besides Roger Federer he is the best mover in the game. He has the best footwork and he is technically very sound. He has to change his mentality of the way he wants to play this game at the very top level.

"His record is great and he is a very strong-minded kid, and I like that, but he needs to recognise when to play offence. I don't think he sees it while he is playing right now and that's the next step for him.

"He is going to have a great future if he gets to the point of recognising balls to attack and to come into the forecourt and play there rather than 15 feet behind the baseline. He will win a lot of slams, he is that good of a mover.

"I think he has plenty of weapons. He hits the ball as cleanly as anybody but you have to learn when to use them and unload on certain balls and I don't see him doing that."

Stefanki, who turned down a chance to coach Murray three years ago because he was not "mentally ready for the baggage" which would have come with the job, added: "You can get through the juniors just being a pusher, a retriever getting balls back.

"I call it negative tennis and that's not going to win you slams. You have to have some offensive threat. He has developed a big serve and can move the ball from A to B as well as anybody, he just does not know when to do it."