THE human debris of Andy Murray's career will not end with the latest parting of the ways from his coach Mark Petchey. A single-minded pursuit of excellence tends to have that effect.

The young Scot is now looking for his third coach inside a year, a fair turnover for a player who has not yet completed 12 months as a full-time tour professional. Time will tell the wisdom of his latest decision, but the motivation is clear. Having reached the top 50, the 18-year-old has now raised the stakes and set his sights on the top 20.

He has deemed that more specialist counselling is required. If only more promising British tennis players, and sportsmen and women, possessed such a ruthless attitude to fulfilling their potential.

Tim Henman, the best British tennis player of the modern era, was criticised for prolonging his association with coach David Felgate. One gets the feeling that Murray would rather throw in the towel than enter a comfort zone.

It is also a decision which fits in with his early career. At 15, he knew that staying in Scotland would hinder him, so he moved to Barcelona, and the Sanchez-Casal tennis academy. Last year, he parted company with his mentor, Pato Alvarez, who he felt was reining in his natural aggression. Now it is Petchey who has paid the price.

Murray's decision to team up with him last summer was met with scepticism in some quarters. An unspectacular playing career aside, it was the 35-year-old's coaching abilities which failed to convince many of the game's leading lights that he was the right man to guide the career of the prodigious Scottish teenager.

John McEnroe raised doubts over Petchey's suitability and Pancho Segura, the respected coach who guided the careers of Jimmy Connors and Andre Agassi, even said that Murray had made the first big mistake of his career.

Alvarez, Murray's former coach who he split with just before Queen's Club last year, was even more damning of Petchey at the time. "How many players have the LTA produced in the last 20 years?", he said. "Should Mark Petchey coach him? Who has he ever coached? What sort of player has he ever produced? Andy needs somebody to coach him who knows how he needs to play."

The 18-year-old's subsequent ascent into the world's top 50, with Petchey at his side, suggests that it was anything but a mistake. That he has been a positive influence on the British No1 is undeniable, particularly as a travelling companion.

It was not hard to see why Murray chose him in the first place. The affable thirty-something was the antithesis of Alvarez. The veteran Colombian coach nurtured Murray's development in Barcelona, but their relationship ended acrimoniously just before Queen's Club, the tournament where Murray made his breakthrough on to the world stage.

The youngster felt Alvarez was trying to temper his aggression style. "He was trying to get me to play in a way that I didn't like, " Murray said. "It wasn't working." But the issue was also personal. The generation gap between them was an issue (Murray was 17, Alvarez 69) and the teenager struggled to relate to a man who was old enough to be his grandfather.

Judy Murray, Andy's mother, admitted as much: "He had been travelling with a coach [Alvarez] he was not getting along with, and that was demotivating him and making it tough.

"This is why it is important now he has people around him who he is confident with and can have fun with while they are working professionally to get him as ready as we can."

If Alvarez was a grandfather figure, then Petchey was more like the happy-go-lucky elder brother. With him at his side, Murray could while away the tedious hours on tour by playing video games or backgammon. The bond between the two was obvious, but the issues at stake were more technical than personal.

"A difference of opinion regarding some aspects of my game, " is how Murray put it in a statement issued last night.

The Herald understands that their professional relationship began to deteriorate as far back as the Australian Open in January. The 18-year-old's aggressive tactics for his match with Juan Ignacio Chela proved to be a big mistake and he lost in straight sets in the first round.

The limitations of his coaching ability, highlighted by McEnroe and others last summer, may have come home to roost. The teenager has decided that he needs a more experienced hand to take him to the next stage, while Petchey's family commitments and commentating duties for Sky TVwere also prohibitive to their continued relationship.

So where now for Murray? He will not have any shortage of offers from coaches keen to work with him, but he has already wisely indicated that he will take time to decide on the next step.

He has picked coaches wisely so far - the next choice could be the most significant in terms of his fulfilling his ambition to enter the world elite.