Demi Lovato: 'Jimmy Kimmel Live' Soundcheck

Demi Lovato rehearses for her performance on Jimmy Kimmel Live in Los Angeles on Monday afternoon (April 1).

The 20-year-old singer performed her hit single “Heart Attack” on the program.

“Getting so excited to perform “Heart Attack” on TV for the first time on @JimmyKimmel Live tonight!!! 11:35/10:35c on ABC!!” Demi excitedly tweeted.

PHOTOS: Check out the latest pics of Demi Lovato

Earlier today, Demi announced that her fourth album, Demi, will drop on May 14th.

“The DEMI pre-order is up on iTunes!! US & Canada get it get it!!!!” she added.