Here's the clearest video we've seen so far of Conor McGregor getting socked hard in the face in the post-fight Octagon brawl at UFC 229 ... and the cage invader lands some pretty solid shots.
The dude in the red shirt has reportedly been identified as Zubaira Tukhugov -- a pro-MMA fighter who's a member of Khabib Nurmagomedov's team.
He's scheduled to fight Conor's teammate, Artem Lobov, on October 27.
In the footage, you can see Tukhugov attack Conor from behind -- connecting with a sucker punch to the side of McGregor's head.
He then pivots and cracks Conor from the front -- landing a barefisted blow to Conor's head.
Ultimately, security comes in and breaks the whole thing up.
Before Tukhugov's attack -- another dude from Khabib's camp sucker punched Conor too ... trying to land hammerfists from the top of the cage.
Dana White said 3 men from Khabib's camp were arrested following the melee ... seems likely these guys were part of that group.