Youthful a cappella group Pentatonix gave it their all and wowed the crowd on 'The Sing-Off' (Mon., 8PM ET on NBC) last night.

The Los Angeles-based group performed their unique take on Katy Perry's song 'E.T.' and afterward seemed real happy with how it went.

Judge Sara Bareilles told the singers how she loved that each member of the group "had your little moment in that song where you just go to shine and to sparkle and we got to see all the dimensions of you."

Will Pentatonix go all the way in the competition and land the $100,000 grand prize? Stay tuned for updates.