Spears and Timberlake were both Mouseketeers on TV's "The New Mickey Mouse Club" in the early 1990s and later dated for several years, splitting up in 2002.

"They are going to be onstage performing with Madonna," E! Online quoted Seacrest as saying on KIIS-FM host D.J. BoyToy Jesse's show Wednesday. "If Justin and Britney end up on that stage with her ... I don't know if I've ever seen anything quite like that before."

Although Spears and Timberlake have both worked with Madonna since their breakup, they have spent little time together in recent years. Spears is a divorced mother of two young sons and Timberlake is dating Jessica Biel after ending his longterm relationship with Cameron Diaz.

"American Idol" host Seacrest is also a correspondent for E! News.