To the uninitiated, the position of tighthead prop on a rugby pitch could merely appear the unfittest and potentially least important. Reality, though, tells a very different story.

As heavy – often heavier – than the tallest players on the field but virtually always far shorter, rugby’s best No 3’s are not athletes you want BMI tested. But, as the best current loosehead prop in the world Ox Nche of South Africa says: salads don’t win scrums.

Tightheads are the anchor of the scrum and must be strong and robust enough to withstand the weight of two opponents pushing against them, trapped between opposing loosehead and hooker. In addition to resisting attacks, for his own side a tighthead must keep the scrum stable and square.

The average weight of elite professional tightheads nears 120kg, while the best are even heavier: Ireland’s Tadhg Furlong around the 125kg mark, South Africa’s Frans Malherbe 144kg and France’s behemoth Uini Atonio 145kg.

Now imagine another of the world’s current top performing tightheads began his competitive sporting journey as a decorated downhill mountain biker. Can there be a sporting transition more unlikely?

For Scotland’s Zander Fagerson, such a passage is his story. And to a British and Irish Lions tighthead at that.

“One of the main things for me was mountain biking. I absolutely loved that,” he tells Sky Sports.

“I was really lucky our parents encouraged us in anything we did. We lived in the middle of nowhere in a small country village called Kirriemuir, outside Dundee.

“As rugby got more physical, tackling players on a Saturday and biking and bumping into trees on a Sunday didn’t really add up.

“We were a very sporty family. When we go home now as adults, we like to remind each other when we’re putting on five-a-side with the kids.

“With my three brothers in the garden the trampoline was pretty much Royal Rumble, as you can imagine. We had a lot of fun.”

One of five, two of Fagerson’s brothers played hockey to a decent standard while his sister played age-grade level hockey for Scotland. Then there’s his younger brother Matt, himself a decorated Scotland rugby international and current holder of 52 caps.

Mountain biking proved not just a pastime for Fagerson, though. In 2010 he won the Scottish Youth Downhill Mountain Bike Championship at the age of 14. Video evidence still exists on YouTube of a teenage Fagerson tearing through his local trails.

Within six years he was selected as the fourth youngest international prop in Scottish history and youngest since Bill Black in 1948, emerging off the bench against England in the 2016 Six Nations at the age of 20.

Five years later he became a Lion for the 2021 tour to South Africa in the midst of Covid – something he says was wholly unexpected when he sat down to lunch at the Glasgow Warriors training ground that May.

“It was never expected. I don’t think any player would ever expect to go on one.

“To see my name read out live was really special and to be surrounded by my team-mates and little brother was a real moment for me, especially going through that tough time with no fans in stadiums.

“It will definitely live with me for a long time.

“To be a British and Irish Lion is the greatest privilege any player can have and the culmination of a lot of years of hard work.

“My team-mates went ballistic. I still remember Oli Kebble going bonkers, it was absolutely amazing. I couldn’t stop smiling all day. Getting selected was a dream come true.”

‘2021 tour was strange, uncertain time’ | ‘Lions debut was pinch-yourself moment’

As Lions tours go, 2021 was like no other unfortunately.

No crowds were permitted at any match due to Covid, while all eight tour matches took place in just three stadiums.

Never before has uncertainty like it gripped a major event in the sport. Reports came out earlier that year detailing the tour could move north to Britain and Ireland where reduced crowds were returning, while there were also suggestions of delaying the series by a year to 2022 or cancelling it altogether.

Such is the custom of Lions supporters travelling in phenomenal numbers, thousands signed a petition to the Lions board requesting the tour stay in South Africa and be postponed to 2022. Australia offered to host the series too with a promise to deliver capacity crowds, but were rejected.

In the end the decision was to go ahead in South Africa without fans, but it’s fair comment to say for any player with a chance of involvement, it was a hugely stressful time.

“It was tough. The challenges and potential changes that were going to happen were totally out of our control,” Fagerson says.

“There was a whole bunch of uncertainty in rugby and all aspects of the game at that time. I remember doing the Autumn Nations Cup and we were locked into a bubble for five weeks to make sure there was no spread or any chance of catching Covid.

“It was strange times. First and foremost, I was just excited the tour was going ahead at all.

“Thinking back, it was four years ago but feels like it was yesterday. To be in work now with no masks on and have fans back in stadiums, I think a lot of us have forgotten about it.”

A back spasm denied Fagerson the chance to make his Lions debut on home soil at Murrayfield in a warm-up against Japan before the squad departed, but he did officially become Lion No 848 when he came off the bench at Ellis Park against South Africa’s Gauteng-based Lions.

Empty stadium or not, it was a moment of immense joy for Fagerson.

“It was amazing, a sort of pinch-yourself moment. You get your jersey with your name on it, your cap number and afterwards there’s the capping ceremony as well.

“I took a moment to think about all the teams and people that helped me get to that point and just took it all in, really enjoyed it as much as I could. It was an absolute, as I keep saying, dream come true. It’s any boy’s dream.

“Back when me and my brothers were playing in the garden back in Kirriemuir, we were pretending to be Lions players.

“Someone like the Scottish prop Tom Smith, you’d try to emulate him in our touch games when we were kids. Then to actually become a Lion is truly special.

“I couldn’t see my family afterwards and give them a hug, and to play in front of them for my first Lions game would have been the ultimate dream, but it was one of those things out of my control. I was just chuffed to get over there.”

‘Not playing in Lions Tests ate me up – the brutal nature of sport’

From the happiness and relief of getting on tour, a professional player’s mindset at the top quickly refocuses: the Test series becomes everything.

For Fagerson, the brutal nature of sport was laid bare. Of the five tour games in South Africa, he featured in four them and scored a try against the Stormers, but ultimately was omitted for all three Tests.

English tighthead Kyle Sinckler – absent from the original tour squad before replacing an injured Andrew Porter – was picked as a replacement for each match against the Springboks behind Furlong.

Instead, Fagerson was in the stands in a tracksuit and mask as the Lions fell to a hugely frustrating 2-1 series defeat on a tour best remembered for the shameful off-field antics of South Africa director of rugby Rassie Erasmus.

“It was frustrating as we wanted to go over there and win the series, but didn’t get that job done.

“It was also frustrating for me because of that back injury. It lagged on a bit and I didn’t feel like I gave the best account of myself. It ate me up a little bit, but you can’t do anything to change that.

“It’s all about winning, isn’t it? The coaches picked their best team and sadly I didn’t make any of them. That’s the brutal nature of sport.

“It’s a coach’s opinion. You’ve done all you can and can’t control it. You just need to try be present and help contribute. I helped the boys prepare as much as I could. It’s a team effort, not an individual one.

“Once you take a step back after the disappointment – and don’t get me wrong, I was disappointed and wanted to play – you think about the bigger picture and what you can do to support. That’s what the Lions is all about, everyone coming together and going for a collective goal.”

Up until June last year, Fagerson had yet to taste trophy success in a nine-year career. That all changed when Glasgow went on a stunning URC run to beat Munster at Thomond Park in the semi-finals and then recover from 13-0 down to beat the Bulls 21-16 at Loftus Versfeld in a fabulous final.

Fagerson improbably played 80 minutes in all three knockout games, and admits the taste of success has made the next target converting Scotland’s promise and competing into titles.

“We’ve got a great Glasgow contingent in camp and it definitely drives you to try and emulate that title with Scotland. But let’s not talk about it, let’s just go out there and do it.”

In terms of personal ambitions for Fagerson, there’s even more motivation to get back on a Lions tour and be part of a Test series this time.

“Becoming a Lion is right up there achievement-wise. After becoming a father and a husband, it’s definitely one of my top three.

“It was an absolutely amazing experience and time has flown by. I’ve added twins and have four kids now.

“I loved it and I’m doing all I can to hopefully get on another one.

“My aim is to get better every training session and pick up those performances I can be proud of. If I can do my role at every game until the end of the season and I’ve done all I can, then what will be, will be. It’s out of my control.”