Justin Timberlake Dating Janet Jackson?

July 12 -- The love lives of Janet Jackson and Justin Timberlake have long been the subject of celebrity gossip. Now it seems the unlikely pair may be dating.

With witnesses claiming the two were locking lips at a star-studded birthday party last weekend in Miami, reports are spreading that they've become the next showbiz mega-couple.

Even by Hollywood standards, this seems like an unlikely pairing: Jackson's a 36-year-old diva and a member of pop music royalty. He's a 21-year-old 'N Sync member who recently said "Bye, Bye, Bye" to Britney Spears.

Neither Jackson or Timberlake has denied the report Thursday in the New York Post that claimed they were getting very friendly at rapper Missy Elliott's birthday party.

"Janet and Justin just started making out in front of everybody," said a witness who wanted to remain anonymous.

Apparently, Timberlake and Jackson were first spotted together two weeks ago by producer Jermaine Dupri, who allegedly saw them bumping and grinding together in an L.A. club.

Fulfilling His Role as Most Eligible Bachelor

Timberlake's spokesman, Ken Sunshine, has done nothing to discourage the rumors.

"Last week People magazine named Justin the most eligible bachelor in the world," Sunshine said. "I guess he's fulfilling that role well. But we never, ever comment on his personal life."

Timberlake and Spears broke up in March. He had recently been linked to 'N Sync backup dancer Jenna Dewan, a woman his own age.

Jackson's side has yet to comment. Michael Jackson's little sister has been married twice. She eloped with James DeBarge in 1984, when she was just 18. It didn't last long. In 1991, she secretly married choreographer Rene Elizondo. They split after nine years.

In an interview after her second marriage with ABCNEWS Radio, Jackson said she's usually the one who initiates a relationship.

"Every one that I've gone out with, I've always been the one that asks," she said. "I've been married twice and the two people I married were the only two people I've ever dated and, um, I don't know how I got the nerve to even ask them out … I asked them out."