Boxing expert Johnny Nelson has told Sky Sports News that age could catch up to 40-year-old Floyd Mayweather against Irishman Conor McGregor.

"The one thing you have to look out for, let's not forget, Floyd Mayweather is 40 years old,” Nelson said.

"He's been out of the ring for a while.

"I know he's top tier, we're thinking there's no chance this guy [will lose], but Conor McGregor is very fast individual, he's got power in both hands.

"We want to see how age has affected Floyd Mayweather.

“In my head, Floyd does it hands down, but let's not forget he's in there against a 29-year-old hungry man that can hit, that's fast and that wants it. So it is not a done deal."

The Dubliner has certainly talked a good game, and on the face of it, has come out on top during the whirlwind promotional tour.

It’s one thing looking and sounding good on a promotional stage, but when it comes to the real thing on August 26, it will be a totally different ball game.

McGregor has never boxed at a professional level, nor has he ever been in the ring with a professional fighter. 40-years-old he maybe, but ‘Money’ Mayweather has been doing it since he was a teenager.

There is one massive disadvantage the 29-year-old possesses that the older Mayweather does not, ring craft. The requisite knowhow of where to put your feet in the ring, when and how to use your hands in attack and defence comes more naturally to the American than too the Irishman.

Sure, McGregor has that to a certain extent, but Mayweather has it in abundance.

This will not be a mishmash of two different fight disciplines like Ali–Inoki in ’76, or when Hulk Hogan took on the Italian stallion in 1982 during Rocky III.

This bout is purely about boxing, and Mayweather wins that everytime.

That breeds a wealth of experience and with a fight record of 49-0, it’s hard to bet against the 40-year-old.