Michael Phelps retired from competitive swimming following the 2016 Summer Games in Rio as the most decorated Olympian of all time — with 28 medals, including 23 gold. But Phelps’ most recent race, which will air Sunday on the Discovery channel, featured his most challenging opponent: a great white shark.

“It was a tough a race, probably the hardest race I’ve ever had,” Phelps told Fox News, declining to disclose the outcome.

Though Phelps has lost very few races in his career, not many people gave him a chance against the shark, perhaps because great whites can reach speeds up to 25 mph, while Phelps clocks in about 6 mph, per ESPN.

[lz_ndn video=32722397]

Not even Phelps’ Olympic teammate, Ryan Lochte, had faith that Phelps could outswim the shark.

“Hell, no,” Lochte told TMZ.

Swimming in open water, “with current and cold water,” was also a big adjustment from the typical pool setting, Phelps said.

However, Discovery outfitted the Olympian with some technology to help even the odds.

“We were able to add some help with the monofin, and being able to have a wetsuit gave a little bit of help toward me,” Phelps said. “I think the odds are pretty stacked in the shark’s favor, but you guys will have to wait and see, to see what happens.”

The 100-meter race took place off Cape Town, South Africa, and had been on 32-year-old Phelps’ bucket list “forever,” he said.

Who do you think would win the Presidency?

By completing the poll, you agree to receive emails from LifeZette, occasional offers from our partners and that you've read and agree to our privacy policy and legal statement.

“It was honestly just something I’ve always wanted to do, being in the water with a shark,” Phelps said. “Whether it’s in a cage, or just swimming freely in the ocean. … Having the chance to literally see these animals up close and personal in their home, it topped so many things that I’ve done — just being able to see how they truly are.

Related: What Is Next for a Free O.J. Simpson?

“I was literally within a foot from two different sharks that were that close to my face — one in a cage, one out of the cage.”

Phelps wasn’t the first Olympian to test his skill against an animal. Track and field legend Jesse Owens once outran a horse in Havana — after getting a 40-yard head start.

So, who knows? Maybe Phelps has a shot after all.

“Phelps vs. Shark: Great Gold vs. Great White” will air at 8 p.m. ET Sunday on Discovery, as part of the channel’s annual “Shark Week.”

Update: Phelps ended up losing his much anticipated race, but was begging for a rematch only minutes after. Perhaps next year.

This Fox News article is used with permission.

(photo credits, homepage images: NewOrca, Fernando Frazão/Agência Brasil; photo credits, article images: Albert Kok, Gage Skidmore)

Read more at Fox News:
‘Arrested Development’ Season 5 Plot Details Revealed By Jason Bateman
Elvis Presley’s First Music Agency Contract Up for Auction
John Cena on Having Kids: ‘I Can Barely Raise Myself’