R&B superstar Rihanna has become a mentor to British girl-group the Sugababes - with the band describing her as their "fourth member."

The pop trio recently signed to hip-hop mogul Jay-Z's Rock-A-Fella music label, and even though they have had little contact with their boss - they have become close pals with label mate Rihanna.

Band member Keisha Buchanan says, "Every time we're gonna hook up (with Jay-Z) he's off partying with Diddy or someone, but Rihanna has been a huge help to us."

"She's been like our fourth member, listening to all our songs and saying what she liked and what she didn't."

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(This news article provided by World Entertainment News Network)