Two girls have recently been linked with Beijing's eight-time gold medalist: US swimmer Amanda Beard and British model Lily Donaldson.
Beard held the Olympic record for women's 200 metres breaststroke after her win in Athens, but failed to reach the final in Beijing. She currently appears nude in a PETA campaign and has posed nude for Playboy.
However, Phelps, has always played down his private life. Before the 2004 Games, the 23-year-old said: "I haven’t got a girlfriend and I can’t do the kind of things all my friends are doing as college students.
"I swim, listen to hip hop and work on my car. But, in my opinion, that’s still a pretty good life. I don’t know whether I’d want to trade it for anything, ” telegraph.co.uk quoted him as saying.