Coldplay will be joined by R&B star Rihanna during their previously announced performance at the London 2012 Paralympic Games Closing Ceremony, which will take place on Sept. 9 in the Olympic Stadium. The Ceremony, called ‘Festival of Flame,' will see the band perform a virtual one-off concert that will be broadcast to an estimated potential worldwide audience of 750 million viewers.

Coldplay and Rihanna are expected to offer up a special arrangement of 'Princess of China,' their hit duet which was featured on Coldplay's most recent album, 'Mylo Xyloto.' "All the closing ceremony details are top secret but Rihanna has already started rehearsing," a source close to singer tells the Huffington Post. "As soon as Coldplay signed up she was with them on stage."

Coldplay reportedly turned down an offer to perform at the Olympics closing ceremony and agreed to play the Paralympics instead, which will be more focused on Coldplay and feature fewer other acts. "The closing ceremony is basically a glorified Coldplay concert," says a source. "They will hardly be off stage."

The band has been working with Paralympic Games Closing Ceremony designer Kim Gavin and Coldplay’s live show co-designer Misty Buckley to organize their production, which will feature a cast of almost 2,000 performers.