Anyone betting on this one?
I'm not a gambler but this would be a tough one to pick. McGregor can rise to the occasion and Mayweather is old and his last couple of fights were snoozefests. On the otherhand, it's boxing and Mayweather knows how to defend himself and score points. I think there's a good chance McGregor knocks him down. McGregor has a relatively large head, for his size, and that helps sustain head punches. McGregor will be an unorthodox fight for Mayweather.
I'll go out on a limb and say McGregor knocks him out.