The outspoken Irishman was present at the MGM Grand on Wednesday, where he went through a thorough work-out for nearly an hour in front of a raucous Las Vegas crowd.
Following the training session, McGregor conducted an in-depth interview with the reporters present, starting with an answer to a question inquiring whether or not he feels grateful that an interim belt was put on the line for his fight against Mendes, since Aldo withdrew.
"Grateful? I'm always grateful for everything in my life," said McGregor.
"But it's the rightful thing to do. [Aldo] didn't show up. Where's the pride? Where's the fighter in him? And then I see him sitting back and him and Chad tweeting back and forth like little buddies.
"When a man is close to death they try and bunch up and buddy up together. They know it's over for them. Let them be little pally pals. We are different people me and [Aldo]. If he grows a set of balls, his time will come too. He will get it as well.
"I think he is crumbling already to be honest. I see a forced persona. He's just different. And then the little back and forth tweets with Jose and he's talking in Brazilian 'Can I have your fans' support please?' and all this bulls***. What is that? That's coward s***.
Whilst the unbeaten McGregor has taken the division by storm, his opponent on Saturday Mendes is a high-quality wrestler and exactly the sort of fighter some of the Dubliner's critics feel he will struggle against.
The 26-year-old McGregor, though, was quick to quash such suggestions.
"I don't think he's the superior wrestler," McGregor continued.
"I've been trained by my Moldovan coaches for a long, long time and my coach John [Kavanagh] is a phenomenal grappler. I feel in the grappling exchanges I'll have the advantage. I'm smoother in the grappling exchanges. We will go out and shut him down.
"I kick fast. When I let a kick go fully. I'll kick him upside his head quicker than he can blink. There are many shots I visualise cracking him. He's coming in here that height. When you're releasing the trigger fully and the target is there [lower], it takes half a millisecond to get from the ground to the head. He is in a lot of trouble and he will know that from the off. I will KO him. Too much power. Too much precision. One round will be enough."
McGregor also revealed that renowned singer Sinead O'Connor will lead him into the ring performing a rendition of The Foggy Dew, his long-time entrance song.
"Yes. The McGregor Show is a spectacle," he said.
"Sinead has been signing me out for a long time so to have her sing live, it's going to be historic."