Rihanna to Guest Judge 'X-Factor'

Rihanna is set to dole out advice for contestants on the U.S. edition of “X-Factor.”

PHOTOS: Rihanna’s Red Hair Evolution

According to TMZ, the pop songstress has been tapped by “X-Factor” judge L.A. Reid to help him decide which contestants to mentor.

Rihanna joins a star-studded lineup which includes Mariah Carey (who will be Simon Cowell’s guest), and judges Reid, Paula Abdul and Nicole Scherzinger.

PHOTOS: Rihanna’s Makeup Evolution

“X-Factor” premieres September 21st. No word yet on the date of Rihanna’s appearance.

Rihanna, said to be working on her sixth studio album, recently showed off her new hair color on the streets of NYC.