Having swapped the octagon for the ring, Conor McGregor may be tempted to depart the square circle to dive in the deep end.
Michael Phelps has challenged McGregor to dip into his world and race the swimmer.
The most decorated Olympian of all time has won a total of 28 medals. Phelps also holds the all-time records for Olympic gold medals.
The swimmer may have been inspired by a recent Saturday Night Live sketch in which McGregor played by Alex Moffat, claimed he was going to follow up his fight with Floyd Mayweather by racing the shark that defeated Phelps.