John Mayer and Katy Perry
and Katy Perry
started and ended Tuesday with each other – and "Who You Love."
Following an early appearance
on Good Morning America
to premiere the music video for their duet, Perry appeared onstage during Mayer's encore in Brooklyn, N.Y., capping the winter leg of his tour
with the first live performance of their song
"Someone I know we all love – me a little more than you – please welcome the fantastic Ms. Katy Perry," Mayer, 36, said as the pop star made her way onto the stage to cheers from the crowd.
After an embrace following the song, Perry, 29, retreated backstage, only to reappear with Mayer and his band for their final bow.
Check out the audience reaction below.