Weightlifter Hafthor Bjornsson barely stuttered when smashing a $25,000 challenge raised to him by millionaire playboy Dan Bilzerian. 

While Bilzerian is more frequently seen adorning social media channels with attractive women and a particularly exuberant lifestyle, he's also a fitness fanatic. 

His devotion to his body can be seen in a YouTube video from 2019, where he spent time gyming with Icelandic giant Hafthor Bjornsson, known for playing The Mountain in HBO's Game of Thrones. 

In the video, Bjornsson shows Bilzerian a 70kg weight with a unique handle - it rotates as you try to lift, requiring the lifter to utilise exceptional forearm strength to maintain the exercise. 

"This is heavy. Anybody in the team can try it, if you can do it, you get a free t-shirt," says Bjornsson after he completes the movement with ease. 

Bilzerian steps up and is unable to lift the weight, being completely outshone by Bjornsson's father Thor, who makes quick work of the weight. Like father like son as they say.

Despite the offering of $25,000 for the next person to do so, nobody is able to lift the weight and Bilzerian's wallet was spared - not that his $200m net worth would be struggling. 

(The challenge starts at 17:30 in the above video)

Bilzerian runs the company Ignite International Brands Ltd, which sells a variety of products including CBD oil and vodka. However, it was reported to lose around $50m last year, largely on marketing and office rental costs. 

There is much scepticism about the source of Bilzerian's fortune, with the former poker player stating it came from his gambling career. 

However, many suspect it comes from a trust fund set up by his father Paul Bilzerian, a corporate takeover specialist.

In 1993, Paul was ordered to pay over $30 million of his allegedly illegal profits to the SEC, but never did as he had filed for bankruptcy.