HAFTHOR Bjornsson, better known as Gregor ‘The Mountain’ Clegane from Game of Thrones, recently rewrote history with a thundering performance at the Arnold Sports Festival Strongman Classic last week with a world record 472kg deadlift.

The towering strongman left the crowd in awe as he exacted revenge after coming second in last year’s edition of the event.

At a terrifying 206cm tall and biceps like tree trunks, Bjornsson has gathered over a million Instagram followers and built an acting career on top of his incredible strongman pursuits.

And little do many know, Bjornsson has an important Aussie working behind the scenes.

Sebastian Oreb, founder of Australian Strength Coach, has been training Bjornsson for over two years as he travels around the world competing against the world’s strongest men.

“His agency had heard about me and paired me up to run a seminar with him and a whole bunch of industry voices in Australia,” he told news.com.au. “He liked what I did and asked me to be his coach — which was a big honour. So of course I said yes. I coached him for the 2016 and ‘17 World’s Strongest Man competitions.”

Bjornsonn came second in both competitions to trailblazing strongman Brian Shaw, whose outrageous pre-competition diets have shocked the world.

Shaw, a four-time World Strongest Man winner and widely regarded as one of the greatest strongmen in history, has his work cut out this year as Bjornsonn reaches his lifting peak at 29.

“Absolutely he can (surpass Shaw),” Mr Oreb said. “He’s an inch taller than him, he’s just genetically gifted. But with the amount of work that goes into being the strongest man on the planet — you just can’t say ‘they’re going to win this year’.”

Behind the imposing frame, Mr Oreb says “Thor” is just your regular bloke.

“He’s a massive dude, he sticks out, but he’s just a regular 29-year-old. He’s got a close group of mates who support everything he does, they travel around the world with him. They just run amok,” he said.

“They’re always in Iceland and people always say there’s not much to do … when I go and live with these guys for one month a year, they just smash each other.”

Sebastian said the Icelandic strongmen undertake brutal dares while training for competitions.

“They’ll see who can stay in the ice baths the longest. I think the record is around 15 minutes. They’ll also dare each other to drink bottles of chilli. It’s the most stupid s***, and I just can’t keep up with it!”

And don’t let common misconceptions of the “grumpy movie star” unnerve you, “Thor” is always up for a selfie and a chat.

“The thing that surprised me about Thor is he’s just a kid. He’s a top bloke. He’s intimidating in appearance but deep down he’s just a legend in every way,” Oreb said.

“He’s taken on (Hollywood fame) extremely well. I’ve been with him when a whole bunch of people are there wanting to take a photo. He’s not too good for anyone. I’ve sat with him at dinner and people have come up to him while he’s got a fork of food in his mouth and he’ll never say no to anybody.”

Oreb left with one simple tip for punters trying to get huge in the gym: “Lose the ego and stay uninjured!”