WATCH: Conor McGregor battles ‘The Mountain’ from ‘Game of Thrones’

There’s no telling whom UFC featherweight champion Jose Aldo is training with ahead of UFC 194, but chances are he’s not battling a 6-foot-9, 419-pound, skull-crushing machine from the HBO series "Game of Thrones."

On Friday, UFC interim champion Conor McGregor welcomed the gigantic strongman named Hafthór Júlíus Björnsson into his gym for some training time on the mats.

For those unaware, Björnsson plays Ser Gregor Clegane, aka "The Mountain" on the "Game of Thrones" in seasons 4 and 5. 

He was charged with engaging in one of the most famous fights during the entire course of the show when he took on Prince Oberyn Martell (played by Pedro Pascal) in an episode from Season 4 titled "The Mountain and the Viper."

Had a good day today with these champs @gunninelson & @thenotoriousmma !

A photo posted by Hafþór Júlíus Björnsson (@thorbjornsson) on

This week, the Icelandic beast took time to stop by SBG Ireland, where he trained with McGregor and his countryman Gunnar Nelson ahead of their fights in December.

Judging by McGregor’s footwork and movement, he might have a shot against Björnsson in hand-to-hand combat — at least until the mammoth heavyweight actually got his hands on the featherweight Irishman.

Just a FYI: It didn’t turn out too well for Oberyn Martell when The Mountain finally got his hands on him, so chances are it wouldn’t turn out much better for McGregor or anybody else in the UFC.