The singer, who has two kids with wife Gwyneth Paltrow, said he was so nervous about asking the Bajan star to sing on Princess of China, from new album Mylo Xyloto, that he ended up looking far from cool.
He told The Sun: 'The album is designed as a whole piece. It has boy and girl lead characters and top of our list for the girl part was Rihanna ... but it took a while to pluck up the courage to ask her. We did a show in Las Vegas and I met her and said, 'Do you think there's any chance?' I was very Hugh Grant-like and spluttering about it. She has such an amazing voice and it's so different to mine. When the vocal happened I thought 'Wow, you sound different' but I think that's also because she was singing a different song to what we are used to hearing from her and it is written by a bloke from Devon.'