A new challenge. After conquering the pool and winning his 23rd gold medal at the 2016 Rio Olympics, Michael Phelps took on a new job Wednesday, August 24 — cohosting an episode of America's Got Talent.

The most decorated Olympian of all time joined host Nick Cannon on stage for the NBC hit's live results show and was greeted with a standing ovation from the crowd as they chanted "U.S.A.! U.S.A.!".

The 31-year-old's fiancée, Nicole Johnson, and their 3-month-old son, Boomer, were in the audience to watch Phelps. He talked about what it meant to have his family in Brazil when he won his historic 23rd gold medal on August 13.

"At that moment was when all the emotions came out. Because I was finally happy with everything I did in my career and I was able to retire how I wanted to," he told Cannon.

"But most importantly," he added, "I had our first child in the stands, watching the race. He wasn't always awake, but it's a completely different experience being able to look up and see your baby boy up there after a race."

Cannon also asked Phelps what drives him to succeed.

"I hate to lose, number one," he said. "My biggest thing was, I started goal-setting at like 9 years old, and I literally dreamt for the stars and dreamt for the biggest possible thing I could think of, so I basically said I wanted to change the sport of swimming and I wanted to do something that nobody had ever done before."

Phelps announced on August 15 that he was hanging up his swimming cap and retiring after making history in Rio.

"Done, done, done — and this time I mean it," he said during an interview with Matt Lauer on the Today show. "I wanted to come back and finish my career how I wanted, and this was the cherry on top of the cake. I'm done. I'm finished. I'm retired. I'm done. No more."

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