Mark Zuckerberg might be the most eccentric of the tech billionaires out there ... 'cause the dude's apparently diving into mixed martial arts, with some skills to boot.
The Facebook founder posted a video Saturday, which shows him training with a fighter named Khai 'The Shadow' Wu ... who's got his UFC debut coming up on Fight Pass. To ring in the milestone, Mark honored his buddy with this clip of them throwing blows.
Check it out ... you see MZ all padded up an going toe to toe with Khai, and wouldn't you know it -- it actually looks like he knows what he's doing.