Michael Phelps -- Back in the Dating Pool

Michael Phelps is a 27-year-old, newly-single Olympic hero ... so it should be surprising to no one that he's flirting with hot chicks less than two weeks after his break up.

As TMZ first reported, Phelps split from the super-hot Megan Rossee just before the New Year.

According to our sources, Phelps (still sporting the porn stache) was hanging poolside on Friday, smoking cigars with his friends and macking on the girl in the yellow shirt.