Murray is isolated at the top the British game
Martina Navratilova says Britain's Andy Murray needs "a change in attitude" to win a first Grand Slam title.
Murray has failed to win a set in his three major final appearances so far, most recently losing to Novak Djokovic in this year's Australian Open final.
"He's got the talent but he's got to get tougher mentally" said the 18-time Grand Slam singles champion.
"Each year [without a Slam] it gets more difficult, the expectations and the pressure get higher".
Murray has slipped to number five in the world rankings and has struggled for form since his 6-4 6-2 6-3 defeat by Djokovic in Melbourne.
"He's too quick to pass the blame, looking at his box and yelling at them as if it's somehow their fault he missed that forehand" said 54-year-old Navratilova.
"I would have thought he would have won a slam by now, though he still has plenty of time on his side."
Murray also reached the final of the 2009 Australian Open, as well as the 2008 US Open final at Flushing Meadows, but he was beaten on both occasions by Roger Federer.
And while Navratilova believes Murray is still in his prime, she says the 23-year-old Scot needs a change of mentality.
The kids coming from the former Eastern European countries and China are hungrier
"He doesn't give his opponent enough credit" she said. "He gets mad when he gets aced - that's a good serve, too good.
"He needs to give his opponent more credit which will take the pressure off him."
Navratilova also feels there are wider failings which have left Murray isolated at the top of the British game.
Anne Keothavong and Elena Baltacha have peaked at 48 and 49 respectively in the women's world rankings, while James Ward is currently Britain's second-ranked male player at number 213.
"You have a bunch of players in the top 100, top 200, top 300 but they don't get to the top 50 or top 10, they can't make that jump," said Navratilova.
"Perhaps they don't have the mentality, the coaches as well as the players themselves don't have the approach to get them from a good pro level to the great pro level.
"I think the hunger definitely plays a part in it. The kids coming from the former Eastern European countries and China are hungrier, they only have that one chance and they grab it."
Murray will look for a return to form in the Sony Ericsson Open in Miami this week.