Subway, the sandwich chain, is banking on the swimmer's transcendent popularity when it launches the first commercials starring Phelps as its pitchman.
"In many ways, Michael breaks the mold," said Tony Pace, the company's chief marketing officer. "Based on all the tracking we do, he's still incredibly highly regarded and his performance is still something people talk about."
Phelps won eight gold medals at the Beijing Games, and Subway signed him to a deal not long afterward. The first ad will roll out Sunday as he prepares to compete at an event that usually doesn't draw much attention: the U.S. national championships, which begin Tuesday in Indianapolis.
That meet, and the world championships later this month in Rome, will be televised on NBC for the first time, a testament to Phelps' appeal.
"It's becoming a more mainstream sport," Phelps told The Associated Press.
The Subway campaign also proves that Phelps' popularity as an endorser survived the publication of a photo showing him inhaling from a marijuana pipe last February.
"As Michael himself was disappointed, so were we," Pace said. "We didn't think it was reflective of who he was and what he's all about. We also thought because he was truly regretful, we thought he was going to be able to get beyond it."
Kellogg Co. dropped him almost immediately, but Subway stayed with him -- even announcing it was doing so the day after he was suspended three months by USA Swimming.
"It just showed they stood by my side and are going to support me through a lot," Phelps said. "To be able to have someone like that who's going to be there through thick and thin means the most to me."
TV viewers will learn Sunday that Phelps favors a meatball sub with jalapenos. Pace said it's likely the company will use Phelps in promotions even during periods when he's not competing.
Phelps plans to enter three individual races at nationals. He's been focused on improving his 100-meter freestyle, but he acknowledged that the schedule at the world meet might prevent him from swimming that event.