Alicia Keys joins Pharrell Williams as mentor on The Voice

Pharrell Williams has recruited R&B superstar Alicia Keys to join him as a guest mentor on reality show The Voice.

Keys will help the Happy hitmaker turn his crop of talented wannabes into stars when the TV talent competition returns to the small screen in September (14).

The two stars will go up against fellow judges Adam Levine and his top advisor Stevie Nicks, Gwen Stefani and her rocker husband Gavin Rossdale, and Blake Shelton and Little Big Town.

Keys and Williams previously collaborated on It's On Again, the theme song for The Amazing Spider-Man 2 movie, while they also worked on the duet Know Who You Are, which featured on the superproducer and Oscar-nominated singer's recent album G I R L.