This time last year Duncan Stewart was driving a delivery van to pick up (no pun intended) some extra cash. Last year he was on £250 a week. Otherwise, in recent years, the Scot has also worked on farms, building sites and an abattoir.

This week he tees it up in the World Cup of Golf where he will be representing Scotland, courtesy of the ultimate of invites from his playing partner Russell Knox. The World No 18 could have gone for Martin Laird, Marc Warren or Richie Ramsay, all three are above Stewart on the world rankings, but he’s gone for someone he played junior golf with in the Highlands before teaming up at Jacksonville University in Florida.

The prize fund down at Kingston Heath this week is a whopping $8m with even the last team being assured of a cut of over $50,000.

Yes, there will be calls of favouritism – ask Lee Westwood what he thinks of the system (Westwood was picked by Danny Willett who then dropped out and his replacement Chris Wood overlooked Westwood in place of Andy Sullivan) – but Stewart’s fortunes are very much on the way up since last winter. This year he played his way off the Challenge Tour and on to the European Tour and the tournament is very much all about being comfortable with your partner – the first and third days are fourball, the second and fourth foursomes.

When did you find out you would be getting a pick for the World Cup? I went out to the Irish Open in May to see Russell, I had week off and he hadn’t seen my son so we went to Dublin. We were having lunch and he mentioned something about the World Cup, I laughed and thought he was joking.

Then he texted me in August, he was off to the Travelers, where he won, and I was off to Sweden and he said he was going to pick me. I was like ‘alright’ but I thought he wasn’t going to joke about that.

He asked if he thought we could beat Jason Day and Adam Scott and I said there was no reason why we can’t and he said I’m picking you then.

The good news is Jason Day has since withdrawn? They’re running scared already. I was absolutely buzzing and played well in Sweden, it gave me a huge confidence boost in the middle of the season and I started playing well again after that. I didn’t know too much about the World Cup and I did some research and it’s quite a big event.

Is it correct that Russell played a part in you going to college in the States? I am a year older than Russ so I had been working at an abattoir and playing some amateur stuff. Some friends were going to New Zealand for a year so I thought that sounded quite good but Russell had visited a few places in the States and he spoke to the coach at Jacksonville, mentioned my name and it went from there.

How did your games compare? We were very similar in lots of ways, perhaps I was less consistent and more erratic, I could go really low but then not so good the next week, Russell was always around 70 but we would always push each other.

How would you describe his game? Given he is in the top 20 in the world, to many he is still something of an unknown quantity? He’s extremely good off the tee, not the longest but so accurate, his iron play and distance control is fantastic and the last couple of seasons his putting has really improved.

How good is he mentally? He’s very chilled out and has a good head on his shoulders. His wife Andrea has played a huge part in where he is today, she used to be a professional tennis player and it’s been a real team effort.

World CupWhen he won the Travelers Championship he threw his cap with something of a flourish, is that his trademark celebration? No, I’ve not seen anything like that before though he got a lot of publicity out of it. There have been a few times when I have seen a fist pump when he has holed a putt at the last to beat me by one.

Have you played foursomes together before? We did in the North District and area teams a few times, never at college. Last time I played foursomes was 2004, he never really moved back as his parents moved out to the States.

How do you think you will cope with the week? I’m obviously going to be nervous but when we are around each we are other very relaxed and you don’t really lose that sort of relationship and that will hopefully play a huge role for me.

Neither of us have been to Australia before. I’ve heard the course is phenomenal and will be firm and linksy which we should like.

Have you played with any big names? I’ve not played with any of the real big names, I played in the same tournaments as Dustin Johnson at college but never with him. I think there will be six or seven Challenge Tour players also there.

What about those who feel like you shouldn’t be playing in a World Cup? There will always be some criticism with this format but the tournament has now gone back to being a team event, and not individual, and that adds more to it. I think Vijay Singh and Jhonnatan Vegas are both playing with their brothers and Victor Dubuisson picked Romain Langasque which is a similar situation to me and Russell, there were four or five French guys ahead of Romain on the rankings.

I am obviously delighted they have changed the format but there is no way he would have picked me if I wasn’t playing well.

Did Russell have the star quality at college? When we graduated, realistically no, but then the work he put in the first two years after that was so impressive. We hadn’t played for two years and we were in Florida and I was like ‘wow’ and he said, very modestly, ‘that’s how I hit it most days now’. After that I’m not surprised at all to see what’s happened since.

Your season has been incredible, first reserve in the first event of the Challenge Tour to earning your card and now this? I was probably going to get in about 60-70 per cent of events, I didn’t have a full category and Team Hydro gave me some invites, including the one where I won in Madrid.

I didn’t play in Kenya, missed the cut in Egypt and then won in Spain.

So where did that come win come from? Being Scottish I like a bit of wind and it was windy in Madrid with tight fairways and firm greens. I don’t want it wide open, a lot of tournaments are set up quite easy and the Tour are looking at setting up the courses a bit tougher.

I had a good year in 2013 and then decided to try and change my swing to get a bit longer, it backfired spectacularly and I basically lost the last two years. I really struggled off the tee with the driver and, not being the longest or now the straightest, wasn’t a great combination.

My son was born a year ago so I had two months off and I thought I’m going to go back to my old swing thoughts and what I used to do. It was a bit weird at first but then I played a few events on the MENA Tour and it felt good and I got an invite into Spain and won.

Didn’t your dad also clean up? Yeah, he had a flutter on me, not for the first time. It was nothing major, a fiver each-way, but it was long odds of 250-1. One of the guys who has some shares on me had £10e/w, thankfully my oddss have dropped a bit now.

And Kazakhstan was another big week… I had a really good weekend, on the Sunday it was chucking it down and freezing and windy and I shot the lowest round of the day to tie fourth there. You know Kazakhstan is like one of your Majors so that is the week where you put a bit of extra pressure on yourself. I nearly earned what I did for winning in Spain. The key on the Challenge Tour is to rack up the top-five finishes, that’s where the money is.

The Challenge Tour is a packed schedule, how do you plan out your year? It is condensed into such a short space, there are 27 events from basically mid April to early November. Last year I played 14 weeks in a row but I wasn’t playing many weekends! In general the ideal is to play three or four weeks in a row and then have a week off when you might not fancy the course very much.

After winning I was playing in the pro-ams so that was great as I would have two nights at home on Sunday and Monday. Then, in the last six weeks, I was home for a total of 18 hours.

How does being a dad help your golf? It has kept me a little bit calmer on the course, I now mark my ball with his name on it. If you get a FaceTime after a round you soon forget about how you’ve played.

Did you come close to packing it in? If I would have had another poor year then I was done and it would have been nothing to do with golf that’s for sure. It crosses all our minds when you’re not playing well and spending a lot of money and nothing coming in. Then it flips on its head.

I did all those jobs and that is a good reality check. I have always had the attitude that I could always find something and it would only be for a few months. I quite enjoyed driving the van, it as clears your mind but, at the same time, it is very different to what you could be making on the course.

Name two players from the Challenge Tour to watch in 2017? Jordan Smith, who won the Road to Oman, and Marcus Armitage. I played with Marcus the first two rounds in Oman and he has got some serious game, I was very impressed. He could be a real dark horse for next season.