After the show honored the notorious "Bikini Girl," Katrina Darrell, with an award for having the best attitude, DioGuardi appeared on stage to perform with the former contestant.
The pair sang a few verses of Mariah Carey's "Vision of Love," a song Darrell auditioned with and DioGuardi critiqued, before DioGuardi ripped open her little black dress to reveal a bikini body to rival her duet partner. Watch the clip.
Darrell auditioned for Idol's season 8 in a bikini and DioGuardi famously criticized her voice and demonstrated the right way to sing the song. Thanks to Simon Cowell, however, Darrell got a golden ticket to Hollywood, but was eliminated in the second round.
At the time, Darrell told PEOPLE she was at a disadvantage because DioGuardi "had it out for me from the beginning ... Maybe there was a little jealousy."
Tell us: Did Kara surprise you? Who looked better in a bikini?