A report Friday night from WBBH, an NBC television affiliate in Fort Myers, Fla., said Phelps will return to swimming with an eye toward competing at the 2016 Rio Olympics. The three-paragraph story on the station's Web site was posted by news anchor Peter Busch, who is the son of Frank Busch, director of the U.S. national swim team.
"The greatest Olympian of all time isn't hanging up his swimsuit, after all," the report said, without citing any sources.
Phelps went on Twitter to downplay the report, but he didn't specifically deny it either.
"Why do I keep getting texts about coming back?" he wrote. "Do (people) really believe everything they hear or read? There are (too) many (people) in the world that think they have a 'story.'"
Busch followed with a tweet that said he felt "very confident with my info. Guess we'll see."
Phelps has said repeatedly his swimming career was over after winning 18 gold medals and 22 medals overall, both totals far more than any other Olympian. He retired at the age of 27 immediately after last summer's London Games.
There was no other immediate comment from the Phelps camp. A message was left with one of his longtime agents, Drew Johnson.
Officials at USA Swimming also didn't immediately respond to a request for comment.
Just last weekend, longtime rival Ryan Lochte was clearly skeptical that Phelps would stick with his decision to retire from a sport he dominated for the past decade, especially when so many swimmers are competing well into their 30s.
"I can't really talk about it," Lochte said, breaking into a sly grin during a Grand Prix meet in Charlotte, N.C. "Who knows?"
In an interview last December with The Associated Press, after beating out LeBron James for male athlete of the year, Phelps stressed repeatedly that he had no plans to return to competitive swimming.
He said London, where he captured four gold medals and two silvers, was the perfect way to close his career.
"I wanted to leave that way," he said. "I'm sure I could come back in another four years, but why? I've done everything I wanted to do. There's no point in me coming back. Everybody is like, 'You're going to come back.' And I'm like, 'No, I'm not.' I've done everything I wanted to do in this sport. I don't know a lot of people who can say that."
After the Olympics, Phelps turned his attention to golf, filming a show with famed instructor Hank Haney for the Golf Channel, signing an endorsement deal with Ping and indicating a desire to see how far he could progress with a new sport. He even joked that the only way he would compete in Rio would be if he qualified in golf, which is rejoining the Olympic program in 2016.
Last week, Phelps participated in an event prior to the Tour Championship at the TPC Sawgrass in Florida.
He also cheered his hometown Baltimore Ravens on their way to the Super Bowl, attending the title game at New Orleans with a large group of family and friends.
Phelps apparently spent Friday swimming at the Interlachen Country Club in Edina, Minn. Lifeguard Stephen Timmes posted a picture on Instagram that showed Phelps, looking extremely fit if not in top condition, smiling and posing poolside.
"Lifeguarded for and swam with Michael Phelps at work today," Timmes wrote. "I love my job."
If Phelps does come back, he would have to wait at least nine months to swim in a sanctioned event under the world anti-doping policy, meaning there's no chance of competing at this summer's world championships in Barcelona even if he could somehow get into condition.
That would peg his return to competition at sometime early next year, leaving plenty of time to get in peak shape and begin gearing up for the 2015 worlds in Russia and, of course, the next Olympics.
The timing of the report was intriguing. Phelps' coach, Bob Bowman, took a sabbatical from the deck after London but was set to work with a group including three-time Olympic gold medalist Allison Schmitt during high-altitude workouts at the national training center in Colorado Springs, leading up to the national championships in Indianapolis next month. Bowman also is coaching the U.S. men's team in Barcelona.
There was no word on whether Phelps might be among the swimmers taking part in the Colorado workouts.