Friday evening Conor McGregor posted a photo to Instagram showing himself standing across from Hafþór J Björnsson, also known as ‘The Mountain’ from Game Of Thrones.

The caption read “Today I had a bare-knuckle fight off a 180kg monster called ‘The Mountain’
I’d never fought, or even seen a man that big before.”

Many doubted that McGregor and ‘The Mountain’ actually had a sparring session, saying the entire thing was a publicity stunt. McGregor then proceeded to post the video of the sparring session to silence critics who doubted the legitimacy of his original post.

Following that, McGregor’s coach John Kavanagh, and teammate Gunnar Nelson took to social media to react to the video, and Björnsson’s visit to the gym. In addition, Björnsson himself took to Instagram to reflect on his training session.

I turn my back for 5 seconds and this goes down!? https://t.co/l7lePoHfro

— Coach Kavanagh (@John_Kavanagh) October 31, 2015

Absolute honor to have my Viking brother visit us training, a beast of a man!! @thorbjornsson #themountain #180kg

A photo posted by Gunnar Nelson (@gunninelson) on Oct 30, 2015 at 11:47am PDT

Had a good day yesterday with these champs @GunniNelson & @TheNotoriousMMA pic.twitter.com/LkR7xComj1

— Hafþór J Björnsson (@ThorBjornsson_) October 31, 2015

No doubt Coach Kavanagh was on the edge of his seat while watching the video in fear of an injury forcing McGregor out of his UFC 194 bout against Jose Aldo.