Christina Perry

And while the drama unfolded during the results show there was a Tyce Diorio Broadway group number danced by the contestants and the All-Stars, a notable performance from Jamal Roberts and Rachel McLaren from the Alvin Ailey Dance Company, a hip-hop routine from Twitch and Comfort and a musical performance from Christina Perry singing her hit single "Jar of Hearts." ...

Source: http://newsroom.mtv.com/2010/07/16/so-you-think-you-can-dance-results-ashley-injured/