Hafþór Júlíus Björnsson is not a man that people would want to mess around with. The 'Game of Thrones' star doesn't just play a strong man on TV; he also happens to be Iceland's strongest man for the past five years. In addition to that, Thor Bjornsson is also a modern-day Viking who has broken a 1,000 year Norwegian record in carrying the mast of the ancient Viking ship Ormrinn Langi. That's no small feat either; the mast weighs more than 1,400lbs.

With all the achievements under his belt, it shouldn't be a problem for the man who plays Gregor Clegane aka The Mountain to take on people half his size. However, the one person who wants to spar with him is Conor McGregor, who happens to be UFC's number one contender in the featherweight division.

The resulting friendly brawl looks like a modern-age take on the classic David vs Goliath fight minus the slingshot. Luckily, there were no skulls crushed in the course of their fight.

For reference, the 24-year-old Thor Bjornsson is 6'9" and weighs almost 400lbs while the 27-year-old Conor McGregor is a foot shorter and only weighs 145lbs.

Conor McGregor is the current UFC Interim Featherweight Champion after defeating Chad Mendes last July. Although he was initially supposed to fight Jose Aldo, the current champion had to pull out due to a rib injury. Conor McGregor and Jose Aldo will fight in a unification match in UFC 194 on December 12.

Hafþór Björnsson is expected to return in the sixth season of 'Game of Thrones' although The Mountain appears to have been in a coma after his fight with Oberyn Martell (Pedro Pascual). In the previous season, it is revealed that Qyburn has revived Gregor Clegane and introduces him to Cersei Lannister as a new member of the Kingsguard.