Katy Perry has covered Rebecca Black's single 'Friday' at a concert in Australia.
The US singer performed the 13-year-old internet sensations surprise hit at the second of two concerts in Melbourne at the weekend.
Perry was backed by two acoustic guitarists for the song – watch the video on Gigwise at the bottom of this page.
Last month, official figures showed Black's 'Friday' had earned more YouTube views than videos by Lady Gaga and Justin Bieber.
The LA teen star's video has scored nearly 100 million views since it was first posted on YouTube on February 10.
Perry is currently in Australia as part of her California Dreams world tour.
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Katy Perry - 'Friday':
Katy Perry - live photos
