"I looked at the crowd," Phelps said. "I saw them yelling and screaming. I saw the priceless look on their faces and I thought, 'This could be pretty big.' "
Pretty big? Phelps' agent, Peter Carlisle, has found out just how big.
"It's beyond anything I've experienced," he said. "If he mentions he likes a certain car, the manufacturer is on the phone with me. Following the VMA awards, we went to the after-party. There were so many people around him that we were moved to the VIP section. Then we were moved to the [very, very important people] section. And he was even mobbed by the VVIP crowd."
In the eye of the whirlwind, Phelps has done something very unusual for him, something he probably hasn't done since he was Javier's age. He has stayed out of the pool.
But Phelps' absence from his comfort zone is only temporary. He plans to dive back into a full workout schedule in January or February with his sights set on the 2012 Olympics in London.
What is left to conquer? Isn't there a limit to how fast a swimmer can go?
"If you put a limit on anything," Phelps said, "you put a limit on how far you can go."
As Phelps left the Leno show late Monday afternoon, he waded into a sea of fans. With their pens, posters and cameras, they lined up outside the studio gate on Bob Hope Drive.
"When I get home," Phelps said to a reporter, "I'm hoping to get back into a normal routine."
The reporter responded, saying Phelps' life will never be normal again.
Phelps nodded.
"I know," he said.