The Irishman threw everything he had at Nate Diaz in the first round of their grudge match at UFC 196.
The Notorious, who said he would KO Diaz inside the first round, threw some big shots the America's way - but Diaz soaked up every single one of them.
That killer left hand which had put the likes of Chad Mendes and Jose Aldo to sleep just wasn't doing the business.
If this wasn't dispiriting enough, Diaz managed to tag McGregor with his infamous 'Stockton Slap'.
Not just once though, he slapped the Dubliner around the face four times during the fight.
For those of you unfamiliar with the 'Stockton Slap' it's pretty much the signature move of the Diaz brothers.
What could be worse than throwing your biggest shots at a guy - then he responds with a b*tch slap around the face and a contemptuous grin?
This is what happened with McGregor. His aura of invincibility was well and truly blown - and then when it went to the ground with jiu jitsu specialist Diaz there really was only going to be one outcome...
https://www.youtube.com/watch?v=A6zxLX1Xg9g
There were some famous faces on Twitter revelling in it...
https://twitter.com/titoortiz/status/706361358950858753?ref_src=twsrc%5Etfw
https://twitter.com/criscyborg/status/706678165817663488?ref_src=twsrc%5Etfw
https://twitter.com/DustinPoirier/status/706359167959879680?ref_src=twsrc%5Etfw
