According to The Sun, Simon Cowell has recruited RiRi to help the former Def Jam chairman chose his final four acts ahead of the live shows.
It is thought SiCo sealed the deal with the S&M hitmaker, after he was spotted dining with Rihanna in her native Barbados last Christmas.
A source told the newspaper: "Simon loves Rihanna and loved having her on the UK show last year — so it's no surprise he wants her back."
They added: "He hasn't officially announced her yet as he loves keeping everyone guessing. But fans are already getting excited."
RiRi is rumoured to the the second guest mentor to sign up for the US series of the talent show, with Mariah Carey apparently confirmed to help Cowell decide who to take through to the finals.
While Rihanna may have made the cut, Cheryl Cole's time on The X Factor USA judging panel has been summed up in a dismal three seconds during a new epic eight-minute trailer for the programme.
Chezza is only seen briefly when the judges give 13-year old hopeful Rachel Crowe feedback, after wowing the judges with her rendition of Duffy's Mercy.
Never mind Cheryl, there's always Britain's Got Talent...
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