'The rematch would be even bigger' - Rory McIlroy hopes Mayweather vs McGregor is a fair contest
McGregor, who has met McIlroy on several occasions at UFC events, is making his professional boxing debut on August 26.
McIlroy, who is an avid fight fan, was asked about the fight at his press conference ahead of this week's Northern Trust.
Asked whether he thought his fellow Irishman stood a chance of beating Mayweather, the former world number said he was.
"Certainly that's all I've done is follow the build up to this thing. Now that I'm off Twitter and social media, all I do is watch YouTube videos of Conor McGregor," said McIlroy.
"I'm intrigued. He [McGregor] talks a good game. If you just listen to his press conferences and what he says, you would think that this guy, he's the one with the 50-0 boxing record.
"It's amazing. I'm a big admirer of him. He talks about visualization and the law of attraction and all this stuff that he believes in it and he vocalizes it, and he has the courage to say what he thinks. I'm a believer in that stuff, and I'm a big advocate of that.
"And some of the stuff he does wouldn't be my cup of tea, but he believes 100 percent in himself and he believes he's going to go out there on Saturday night and shock the world.
"I'm interested just to see how it all plays out, but I just fear that they do all this trash-talking and they go behind the scenes and they are having a laugh and thinking: I can't believe we are talking all this public for a ride.
"We are all buying into it and they are like, can you believe these people believe this. I just hope it doesn't turn into it and I hope it's not in any way fixed.
"It's amazing, like we were talking about, imagine McGregor knocks him out in the first couple of rounds. They would get even more for the rematch. The rematch would be even bigger.
"I just don't know what that zero on Mayweather's record is worth, and that's the thing. That's his legacy. If he goes down and lies down for ten seconds at some point in that, you know, is that worth making an extra few 100 million? That's sort of up to him."