Rihanna has added a little controversy to her upcoming Diamonds tour by announcing she'll be taking outspoken rapper A$Ap Rocky on the road with her.

The star hit the headlines at the MTV Video Music Awards in September (12) after grabbing Rihanna's butt during a joint performance.

But it seems the cheeky move didn't upset the Umbrella singer too much - she has invited him to open for her when she tours North America next spring (12).

Announcing the news via Twitter.com, Rihanna writes, "This is gonna be some Young Epic Rockstar s**t! See you on tour."

Rihanna's Diamonds tour is scheduled to begin with a show in Buffalo, New York on 8 March (13).