Since he has crossed over into boxing, Conor McGregor may as well take on the best of the best in all sports and not just the combat ones.
It's after he was issued with a tongue-in-cheek challenge from swimmer Michael Phelps.
Phelps has dominated in the pool since he won the first of his 23 Olympic Gold medals at the Athens Games in 2004.
However, it was the Games in Beijing 4 years later where he truly made his mark, as he claimed 8 Golds, the most of any athlete in a single Olympic Games.
He was an interested viewer of McGregor's bout against Floyd Mayweather, which saw the American claim the victory by a TKO.
And now it seems Phelps fancies his chances against the Notorious in the pool.
It was clearly a joke, but it seems the best of the best all seem to acknowledge the draw that is Conor McGregor.