The Keeping Up With The Kardshians stars didn't receive the warmest reception as they took to the stage at the MGM Grand in Las Vegas to kick off their brother-in-law's performance.
Oh dear. But, ever the professionals, the teenagers kept smiling as they delivered their lines and didn't miss a beat.
Their arrival to the stage marked the end of the Billboard Music Awards, as Kanye closed the show with a performance of 'All Day' and 'Black Skinhead'.
Kendall, 19, and Kylie, 17, both wore Balmain to the star-studded show.
Their appearance at the Billboard Music Awards came the same night E! aired a Keeping Up With The Kardashians special episode in which Bruce Jenner broke the news to his family that he is transitioning into a woman.
Why is Kendall famous? Find out below!
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