Rebecca Black joined Katy Perry on stage for a cover of her online sensation 'Friday' at a gig in Los Angeles at the weekend.
The teen star, who became a YouTube sensation with the song earlier this year, was greeted by huge applause by the audience.
"Give it up for the infamous Rebecca Black," Perry said.
After completing the song, she added: “Thank you so much Rebecca. That was our moment. We love you Rebecca, give it up.”
'Friday' has become a staple in Perry's set on her California Dreams world tour.
Meanwhile, Black also attended the Teen Choice Awards on Sunday (August 7), where she was named Choice Web Star in honour of her online success.
Katy Perry and Rebecca Black - 'Friday':
Katy Perry - live photos