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.