The 41-year-old television personality revealed he had a one-night stand with a "mega pop star" in his memoir, Just Between Us, and multiple sources tell Us Weekly the person was Britney Spears.
Lopez detailed the rendezvous October 2 on The Ellen DeGeneres Show, but declined to give an actual name. He did tell DeGeneres the encounter happened "maybe six or seven years ago... eight years ago?" in Las Vegas, and said he and the woman are still friendly.
Lopez and Spears were both single at the time of their potential hookup. The television host was on a break from then-girlfriend Karina Smirnoff between 2006 and 2008, and the singer split from husband Kevin Federline in 2006.
Lopez went on to marry Broadway dancer Courtney Mazza in December 2012. The couple have a four-year-old daughter, Gia Francesca, and a one-year-old son, Dominic. Spears is mother to nine-year-old Sean and eight-year-old Jayden James with ex-husband Federline.
Just Between Us was published September 30.