Britney's feeling the heat to shape up her act, and it's not from K-Fed's attorney. It's her labelmate, up-and-coming singer Samantha Jade who inadvertently put the pressure on the pop tart. Brit's label, Jive, set up a $500,000 music video shoot for "Piece of Me," which was scheduled for last Tuesday, but Britney refused to show up. That is, until they told her that they were giving the video shoot to Samantha Jade for her single "Eyes on Me," an insider tells Page Six. "They were going to recalibrate it for Samantha, because it was too expensive to just scrap," the source says. "Britney finally showed up [12 hours late] when she realized a new, younger, hotter girl would take her slot."

Hmm, we wonder if that would work for cleaning up Amy Winehouse's act...