BANG average is the phrase Leon Smith uses to describe his abilities as a tennis player. Thankfully, for the sake of British tennis, he wasn't particularly outstanding when it came to his studies either.

It was a combination of these two demerits which first led to Smith knocking on the door of then Scottish national coach Judy Murray shortly before the turn of the millennium, setting in motion a chain of events which sees the Glaswegian lead a Great Britain team into this weekend's Davis Cup final as strong favourites to land their first title in the world cup of team tennis since 1936. His journey from such humble beginnings is the perfect metaphor for the unlikely rise of his team since he took over the captaincy from John Lloyd in 2010.

"I was bang average as a player," said Smith. "I lived across from a tennis club, I played for Scotland many times, I played in British national championships. It's not like I didn't play, I just wasn't that great.

"But that is why, when I left school at 17-18, and wasn't going to college or university, it was coaching, because obviously I wasn't going to make any money playing," he added. "I didn't have many options. The Scottish Highers or A-Levels were non-existent so university wasn't feasible. I loved coaching, though. Even now if I am asked to do a clinic for any of our sponsors or charities I love getting on court with the younger ones and helping. For me next week, if I was asked if to go and be a club coach again, I could do it. I enjoy it a lot. It doesn't matter what level."

That meeting with Mrs Murray, as Smith says, was "where the journey started". There then followed an apprenticeship of sorts, working in changeable conditions on outdoor courts on the West of Scotland, "sweeping snow off the courts and that sort of thing", while also hitting with a "few good Scottish juniors because I could still hit a ball pretty well".

One of these, of course, was a young Andy Murray. "They were normally getting the better of me," he recalled, "because it was pretty easy to play against me, and she [Judy] had the tactics sorted. I saw the boys from a young age, they were always traipsing around. And that is how, four years into that coaching journey, I got an opportunity to go and work with Andy and others. You need doors to open and you need to commit yourself to the job and I did commit myself to that job."

While he could also rely on the patronage of the future World No 2 when it came to the suggestion he would also be perfect for the Davis Cup captaincy, he couldn't automatically count on his availability. Indeed, it took a while for Smith even to be persuaded that accepting the position was in his best interests, in a situation where he was regarded as a left-field candidate, ill-qualified compared to more high profile figures like Greg Rusedski.

The situation surrounding the team wasn't exactly auspicious either. He acquired the wreckage of the John Lloyd era - the Englishman had fallen out with Andy over his non availability for ties, with even Jamie giving his tuppence worth - and his first tie was a relegation play-off with Turkey with the loser destined to drop to the fourth tier of Davis Cup play, a humiliation from which nations don't always return. As it was, Jamie Baker, James Ward and Colin Fleming all contributed to a 5-0 whitewash against a Turkey team including a player, Marsel Ilhan, who ended that year as World No 77.

"I was surprised to get his position - of course I was - as there was a whole raft of former players, British players, and coaches, who would have had a much, much stronger CV than me," says Smith. "It took a while for me to decide whether to do it or not. I would have said it went as far as me saying no the first time I was asked and then having further chats with them. But once I did, you go in, make a plan of how you want to go on this journey with the players, how you want to prepare the team, and run the team, and most of the things I started back in 2010 at that glamorous Turkey tie have actually stayed. They have just become a bit more well-oiled along the way."

Thirteen ties later, with only two of them losses - one to Italy in Naples in April 2014, and one to none other than Belgium at Braehead in 2012 - and Great Britain stand on the verge of their first Davis Cup title for 79 years. Their progress has surpassed even Smith's initial expectations. "At the start of that week against Turkey I was trying to be so organised, even though I was a complete rookie at the time," he said. "I remember writing something on the flip chart before addressing players that we were going to be 'a well prepared team on a journey back to the World Group'. Back then it was just about trying to establish that we were going to prepare very well and if I went too far with the preparation then so be it."

Victory against Slovakia was important for gathering momentum, coming back from two-love down against Russia in Coventry was a huge moment, and so too was being able to welcome Andy Murray back into the fold for the 4-1 World Group play-off win against Croatia in Umag. Louis Cayer's work in the doubles has been another cornerstone. "There is a group of staff that have been on that journey from the start which is really nice," said Smith. "A few have come and gone for different reasons, but the mainstay is generally the same. Some observers will say, ‘Oh you’ve got far too big a support team – it is massive’. But I was not exactly breaking the bank. These are mainstay British coaches who would do it for free."

If that group has become like a second family to Smith, his real one - he has a wife and three children - will also be over in Ghent for the tie too. "The whole clan is coming out," says Smith. "It will mean a couple of days off school so the kids are happy ... but the payback is that I have to do a talk to the senior school and primary school when I come back."