Stop it. J. Lo wouldn't need a guest. She's gotten hits since 99 just as long as Britney and Beyonce.

She can easily fill out a 5-6 song set.
Get Right, On the Floor, Jenny from the Chopping Block would be her staple 3. Then, she can choose btwn. If U Had My Love, Lets Get Loud, Divorce Dnt Cost a Thing, or Waiting for Tonight or Im Real for an extra.