Elon Musk has been pictured hitting the practice mats with a popular Brazilian jiu jitsu black belt ahead of what could be a bizarre blockbuster bout against Facebook founder Mark Zuckerberg.

Despite some pushback from the public, Musk has commenced training for his MMA cage-fight contest with fellow billionaire media mogul Zuckerberg, taking part in a training session with black-belt podcaster Lex Fridman.

Fridman, who has also trained with Zuckerberg, said he was 'extremely impressed' with Musk's ability - but he would prefer if the pair didn't end up trading blows.

'I did an impromptu training session with @elonmusk for a few hours yesterday. I'm extremely impressed with his strength, power, and skill, on the feet and on the ground,' Fridman posted alongside photos of the pair grappling.

'It was epic. It's really inspiring to see Elon and Mark doing martial arts, but I think the world is served far better if they train martial arts but not fight in the cage.'

'That said, as Elon says, the most entertaining outcome is the most likely... I'm there for them, no matter what.'

Meanwhile, Musk has received a sensational offer from UFC legend Georges St-Pierre to help him prepare for the blockbuster bout.

'Elon Musk I'm a huge fan of yours and it would be an absolute honor to help you and be your training partner for the challenge against Zuckerberg,' GSP tweeted on Saturday.