Chris Martin was scared to ask Rihanna to sing on Coldplay’s new album.

The singer- who is married to Hollywood actress Gwyneth Paltrow – had to “pluck up the courage” to ask the ‘Only Girl (In The World)’ hitmaker to appear as a guest vocalist on track ‘Princess Of China’ from new album ‘Mylo Xyloto’.

He said: “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 guy from Devon.”

Despite Coldplay selling more than 50 million records, Chris admits the band have to “deliver or quit” with their fifth album, although he is confident fans will “really like” the new album.

He added to The Sun newspaper: “We’re getting to the age where you’ve got to deliver or quit. Just because we were popular then, doesn’t mean we are now.

“Anyone who buys the album will really like it, except if they really don’t want to like it. Then they’ll have to wait a year, and then admit they like it.

“The thing you have to accept in return for having very loyal fans is you have a lot of other fans that want to kill you. And that’s OK. It’s hard to accept at first but after a while you have to be comfortable with it.”

‘Mylo Xyloto’ will be released on October 24, preceded by a single ‘Paradise’, which was released today (12.09.11).