Phelps' hilarious defence of fake shark race

Michael Phelps has defended his 'race' against a great white shark by inviting disappointed fans to try a real swim for themselves.

The American swimmer took part in a Discovery Channel documentary to find out if he could beat a shark over a 100m race.

But all was not as it seemed, with Phelps' actual swim off the coast of South Africa edited to put him in a race against a computer-generated shark.

“If somebody actually wants to get in the water and race side-by-side with a great white, go ahead,” Phelps said.

“You’re not going to get the shark to swim in a straight line. And, uh, yeah, it would be interesting to see. We’ll leave it at that.”

The shark's speed was calculated by experts and extrapolated to 36.1 seconds over 100m.

Phelps wore a monofin and finished an open-water 100m butterfly swim in 38.1 seconds.

"For those who are disappointed I'm sorry for that," he said on Facebook.

"But I absolutely had one of the most exciting two weeks of my life being able to dive with these animals, see these animals up close and personal."

Phelps went on to defend himself further, saying he was open about the situation in interviews prior to the original broadcast.

"Some people just decide not to listen to some of the things that we do, and that's not my fault that you don't do that," he said.