Lady GaGa's younger sister made a cameo in her 'Telephone' video, according to the promo's costume designer.
Brunette Natali Germanotta, 17, can be seen wearing sunglasses and standing behind the popstar in an early scene from the jail sequence of the video.
Speaking to E! Online, designer Brian Lichtenberg - who devised GaGa's crime scene tape outfit - said: "When she is on the phone in jail, there's a girl behind her that's in the frame that looks a lot like GaGa. That's her sister."
The nine-minute promo - which also features Beyoncé - premiered on E! News last Thursday, and has already been hailed as the most popular music video ever, clocking up 14 million hits on YouTube in just three days.
GaGa previously revealed that she wanted the music clip - directed by Jonas Åkerlund - to be a social commentary on the technological state of America.
Click here to watch the official 'Telephone' video
