HARK 1, Michael Phelps 0.

The Olympic swimming legend lost by a fin in the battle of man versus beast on Sunday night as he went head to head with a Great White to kick off Discovery's Shark Week.

The 100 metre "race" - dubbed "Great Gold vs. Great White" - ended in dramatic fashion, with Jaws edging out Phelps by just 2 seconds.

The shark, age unknown, managed to swim the length of the open ocean course in 36.1 seconds - while the Olympian did it in 38.1.

Those hoping to see the underwater opponents swim side-by-side, possibly in a pool of some sort, did not get their wish as they each took turns running the 100 metres at different times.

But there was still a chance of Phelps getting bitten, on account of him swimming in the shark-infested waters off the coast of South Africa - described by experts as "the White Shark's realm".

To assure his safety, Discovery placed numerous divers around the Olympic gold medallist to keep an eye on the predators.

Discovery later super imposed an image of the shark on the other side of Phelps to give the appearance of an actual 100 metre swimming race.

Braving the frigid 11C waters, the 32-year-old ultimately tried to beat the shark's time by using a "monofin" and 1-millimetre-thick wet suit.

To be fair, Great Whites can swim up to 40km/h, which is light years ahead of Phelps' top speed of 10km/h per hour.

Experts described on the show how the Olympic superhero actually stood a chance against the much-faster shark thanks to his endurance.

While the Great White swam the race at a slow pace - with brief bursts of speed - Phelps attempted to outpace the shark by cruising and maintaining the same steady rate.

But it wasn't enough to score the victory.

"Rematch?" Phelps tweeted afterwards. "Next time..warmer water."