My money's on McGregor.

Yes, they're fighting under boxing rules and yes, Mayweather is one of the best defensive boxers ever, but here's the thing - Boxers are trained how to box. Mix martial artists are trained in how to fight.

McGregor has the raw power to knock Mayweather out and is predominately a striker. The majority of his wins are TKOs and KOs via punches. His style is to win fights with punches.

Mayweather has amazing technical skill, and can potentially defend himself, but I don't see his offense as too threatening to McGregor, especially since his last TKO was 10 years ago.

With this in mind, Mayweather is used to defending himself from other boxers, trained to box. He's never had to defend himself against someone who will be all out to knock him out, instead of scoring points. McGregor knows there's no way he can outbox Mayweather. He's going in there with the intention to knock Mayweather out (as he's been boasting), not box with him.

Here's my prediction - McGregor will either knock Mayweather out (TKO or KO) or Mayweather will keep him back enough to win via decision.