U.S. Olympic swimmer Michael Phelps has won 23 gold medals in the pool but he will take on a great white shark for the opening night event of Shark Week 2017 on Sunday night.

American Olympic swimmer Michael Phelps, 32, is the most decorated Olympian of all time but his decision to race a great white shark that can swim up to 10 times faster than a human being may have him looking like the fish out of water. The Discovery Channel’s annual Shark Week will kick off Sunday night with the Phelps vs. Shark event.

“[Phelps] is our greatest champion to ever get in the water ... but he has one competition left to win,” the Discovery Channel’s promotion reads. “Michael Phelps makes a splash with the most interesting race of his career, and gets schooled on everything ‘shark’ at the Bimini Shark Lab.”

Read: Michael Phelps vs. A Great White Shark: Everything You Need To Know

The Discovery Channel hasn’t officially released much information about the race itself, but Vanity Fair reports “the two will each swim 100 meters in the same open water, and their times will be compared.” However, Phelps himself has indicated that he and the shark were not going to be in the water at the same time.

Phelps, who has described himself as a longtime “Shark Week” fan, has 28 total Olympic medals. But his 6-miles-an-hour recorded swimming speed will likely not succeed against a great white shark, which can swim 10 miles per hour on average and 35 mph at top speed.

#TeamPhelps or #TeamShark?

Regardless, Phelps says he welcomed the opportunity to race a shark on a monofin or right in the water. He explained that coming face-to-face with such “majestic creatures” for the Shark Week 2017 opening event is a dream come true.

“I was like, ‘Yeah, sure, why not? Let’s see who would win a race,’” he told EW. “It’s hard for me to race something that has the speed that they have, and how fast they can turn on a dime is something that’s truly incredible, especially with the size of these animals. I got in and did my best, and you guys are going to have to see what the outcome is.”

Phelps will take on another challenge with "Shark School With Michael Phelps" to air on July 30. He will swim up close and personal with a 13-foot hammerhead in the Bahamas.

The Phelps vs. Shark race will air at 8 p.m. EDT on Discovery Channel.