• PUMP IT UP photo | Britney Spears

Credit: John Shearer/Invision/AP

Published: Monday May 13, 2013 06:00 AM EDT

2013

PUMP IT UP

After revealing her slimmed-down bod in Shape magazine, Britney Spears trades in her bikini for an equally sexy Roberto Cavalli LBD at Saturday's 102.7 KIIS-FM's Wango Tango music fest in Carson, Calif.