Coldplay frontman Chris Martin says he was scared to ask R&B star Rihanna to appear on the group's new album Mylo Xyloto.

The 34-year-old rocker, who is married to actress Gwyneth Paltrow, says Rihanna was the first choice for the girl's part in their album.

"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," he said.

Despite Coldplay selling more than 50 million records, Martin admits the band have to "deliver or quit" with their fifth album.

"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," he added. Mylo Xyloto will be released in October.