The world’s most decorated Olympian may have finally met his match.

Phelps raced an 8-foot great white shark in open water Tuesday as part of Discovery Channel’s Shark Week. The race airs at 8 p.m. Sunday.

The episode is called “Phelps vs. shark: Great gold vs. great white.”

Phelps wore a special wet suit with a monofin attached to his feet.

The fastest Phelps ever swam to reach a gold medal was roughly 6 miles per hour, but with the monofin, he doubled that speed. Great whites can swim up to 25 miles per hour.

Phelps said he felt totally safe the whole time, surrounded by safety divers during the race. He told Jimmy Fallon on The Tonight Show that he originally wanted to do it without the protective cage.

“I told my wife I wanted to do it without a cage, and she said, ‘Well we have a family. I don’t know if that’s really going to fly,” Phelps told Fallon.

According to an Instagram post, swimming with a great white is something Phelps has always dreamed of doing.

I was able to do something that I had always wanted to do. Be in a cage and dive with great White sharks 🦈!! #bucketlist

A post shared by Michael Phelps (@m_phelps00) on