The most decorated Olympian of all-time was unable to out-swim the ocean's most dangerous predator.
Michael Phelps - a 23-time Olympic gold medallist - lost out by two seconds in the "race" between man and beast to kick off Discovery's Shark Week.
Dubbed the "Great Gold v Great White" battle, the two never actually directly raced eachother around the open ocean course.
Instead, both ran the course at different times, before the footage was edited to make it appear as if it was an actual 100 metre swimming race.
However, there was a chance Phelps could have been bit, with the open ocean course located in shark-infested waters off the coast of South Africa.
While Phelps lost out, he took to Twitter to let the Great White know he is keen for a rematch, just on his terms.