MARK Petchey has tales about the teenage Andy Murray that might make your toes curl. Like the time the Scot was sitting in a rental car on a gridlocked New York street, cheerfully pamping the horn at all and sundry, leaving his coach fretting that the NYPD might stage an intervention. Or how about the night the uber-competitive youngster spent all night in an upstairs room in Petchey's house, furiously battling away to beat his daughter's record on children's toy Bop-It. So it is somehow counter-intuitive when the Scot's former coach and Sky Sports pundit reveals that one of the best things about his former pupil is how little he has changed in the decade since he used to chaperone him around the globe.

"He's slightly less annoying than the guy who was pressing my horn in the middle of New York, with me worrying about us getting shot," says Petchey. "But genuinely one of the most beautiful things about him is he hasn’t changed as a person. He’s obviously changed as a player, he’s become so physically dominating on court, worked hard on the things he perhaps didn’t love when he started out. That’s a tribute to him. But the one thing that hasn’t changed is that he’s so authentic. What you see is what you get, love him or hate him. That says a lot about him.

"Money changes a lot of young kids and he got a lot quite young," the Englishman added. "That can really tilt your moral values, change who you are as a person. But as well as being authentic, he’s consistent. You don’t get the ups and downs, he treats you the same all the time. Whether he’s competing at Wimbledon or on an off-week, he’s the same off the court."

Having overseen Murray's big breakthrough at Wimbledon ten years ago, Petchey left his job at the LTA to work with him full time, their year together seeing him break into the top 50. Since then, of course, the Murray legend has been built on the back of two Grand Slam wins and an Olympic gold, but with everything, individually and collectively, that is riding on it, Petchey reckons that bringing the Davis Cup back to Britain this weekend or the first time since 1936 might just top the lot.

“I said to Leon [Smith] after the Queens’ tie that his win against [Gilles] Simon, after what he’d been through at Wimbledon with all the pressure that’s put on him, was arguably the bkiest British performance of the year," said Petchey. "It’s very easy to get lost in the fact that Andy’s ranked No 2 in the world and he should beat these guys. But to know that if you lose that match and you’ve lost the tie, your dream, and to come back from position, was incredible to me. If they win the Davis Cup Final it will be one of the greatest achievements of his career - if not THE greatest, with all the different pressures."

Everyone, including Andy Murray himself, is at pains to point out that Great Britain's Davis Cup team are not a one-man squad. The likes of his brother Jamie, Dan Evans, James Ward, Ross Hutchins and Scotland's Colin Fleming have all made contributions to the journey back from Euro/Africa Zone II and the likes of Jamie, Ward, Kyle Edmund and Dominic Inglot could yet help Britain get over the line in Belgium. But in truth, Petchey is well aware how reliant British tennis is on the World No 2.

"Leon [Smith] has made some big calls and 98% of them have come off, so Britain are there because of him too," said Petchey. "Jamie was the go to guy in France and played well enough against Australia as well. But every team has a franchise player and Andy is ours. The pressure that is on him to win, three matches sometimes, is ridiculous and yet time and time again he comes through it. It’s one thing heaping the pressure on yourself but it’s another thing thinking that you could be potentially letting other people down if he fails. He’s unique in the respect that if he loses one of his matches, we lose the tie. We are sitting here talking about winning the ultimate team competition in the world, along with Jamie and a couple of cameos we’ve had along the way, he has been the rock."

The flip side of that, of course, is just how barren a place British tennis will become when his body finally gives way and he decides to hang up his racket. “We, the people who work in this industry, are incredibly fortunate to have had him," added Petchey, speaking as David Lloyd Leisure installed a special rebound wall at a Cambuslang school recently. "It’s hard to put into words what it has meant to us to have been able to be a part of his journey to the latter stages of all these tournaments. His consistency has been right up there with Novak’s. Okay, not the tally of Majors, but his consistency at being at the back end of tournaments is right there with these guys.

Without him? It’s a gaping hole, isn’t it? Hopefully nobody is running away from the fact that when Andy goes, the enormous canyon that he has been papering over will be laid bare. We need to make tennis cost effective, not cheap, because tennis across the world is expensive, but we need to find a way to make it as accessible and affordable as we can. So that we are not sitting here with a desert which is coming towards us rapidly when Andy stops playing. Without him, it’s going to feel unbelievably barren.”

Until then, Scotland and Britain should just revel in one of the most amazing tales in more than a century of Davis Cup action. "Dunblane could win a Davis Cup," said Petchey. "It is amazing, but it is true. They [Andy and Jamie], on their own, could win it. And fair play. It is a great story and they are great guys. What other way would you wish it to happen?"