Rihanna, Pharrell Guest Judge on 'X Factor' [Video]

Rihanna and Pharrell lent their expertise to the contestants on last night’s “X Factor.” RiRi joined former Def Jam executive L.A. Reid at his Hamptons home as she judged the boys, including 14-year-old Brian “Astro” Bradley, who she likened to a “mini J. Cole,” and Phillip Lomax, who charmed her with his cover of “Don’t Stop the Music.”

“I’m definitely looking for individuality, star potential. Just have fun, knock it out the park, and good luck,” the pop superstar told the aspiring artists, who hope to score the $5 million recording contract prize.

Meanwhile, Pharrell was over at Paula Abdul’s house mentoring the groups. The N.E.R.D. frontman watched a country cover of “Born This Way” and acoustic version of “Only Girl (In the World)” performed by two brothers.

Nicole Scherzinger called on her friend Enrique Iglesias to critique the over-30 contestants, while Simon Cowell’s guest judge Mariah Carey was a no show because her flight was grounded due to Hurricane Irene.