But just as the world was ridiculing McGregor's boxing ability, UFC president Dana White released clips of the much talked about sparring sessions between the Irishman and former boxing champion Paulie Malignaggi.
The boxer lashed out at McGregor after their heated sparring sessions last week.
Malignaggi said he was set up and made to look stupid by the McGregor camp after "beating up" McGregor - but the UFC star returned serve.
"He can say what he wants. He got his ego badly dented," McGregor told reporters. "He got his a** whooped. He was flattened, what can I say. It did not go well for him.
"When I was hearing all the stuff he was saying, I said, 'it's concussion talk', the man was badly badly concussed. I mean look at his face, he got busted up bad."
While Malignaggi asked for the UFC to upload the full sparring session, White has released two short clips, that show McGregor in a positive light.
In the first, McGregor rocks Malignaggi with a heavy left hand that stuns the American and leaves him stumbling towards the ropes. While the second clip shows Malignaggi falling to the canvass after a McGregor combination - although referee Joe Cortez seems to call it a slip, just as the clip concludes.
Despite the criticism, "Mystic Mac" returned ahead of his showdown with Floyd "Money" Mayweather and he's predicting a quick night's work.
Conor McGregor is known for making bold predictions before a fight and he used his media workout to declare his latest.
Floyd Mayweather has proposed the two fighters sport eight-ounce boxing gloves for their August 27 (AEST) showdown, something the Nevada Athletic Commission will vote on next week.
But McGregor has sent a warning to the undefeated boxing legend, saying he doesn't see the fight going very long if he's allowed to sport the lighter gloves.
"Trust me if we're eight ounces, I'm struggling to give him two rounds," McGregor told reporters. "That's the god honest truth. The only reason I maybe give him two rounds is because in this game, the referee stops me pounding his head into the canvas and he gets ten seconds to recover.
"That's the only reason he might get to the second round. If it's ten ounces, maybe four rounds.
"I will knock him out bad - he is too small."
The Nevada commission typically mandates 10-ounce gloves be worn in boxing bouts at 147 pounds (66 kilograms) or heavier. Mayweather and McGregor is taking place at 154 pounds (69kg).
But given the fact a 49-0 fighter is facing someone on their boxing debut, it's not the first time traditional rules have been altered in the unique showdown.
McGregor held his media workout in Las Vegas on Friday (Saturday morning AEST) and said he had watched Floyd Mayweather's exhibition a day earlier, and wasn't impressed.
"I see a beaten man in his eyes, in his body language, in everything he does," McGregor said.
"In my mind, it's an easy fight."
When asked what makes him so confident heading into what is the biggest test of his combat sports career, McGregor offered a short response. "I get it from hard work," McGregor said. "I get it from the work I put in."
McGregor also used his session to blast his critics in the media. Some commentators have said he and Mayweather have turned the fight promotion into a sideshow. But the Irish UFC star told those present at his training session that they should embrace the fact he is different.
"Don't act like you're not excited by all this," McGregor said. "You're sick of the boxing game, you know it.
"You're sick of everyone in the boxing game, same s***, same boring s***.
"To all of boxing. It's OK to love me as much as I love me."
