Rihanna thrilled revellers at London's Wireless Festival on Sunday (14Jul13) when she joined her mentor Jay-Z on stage for a surprise performance of their hit track Run This Town. The 99 Problems hitmaker took to the stage alongside his frequent collaborator Justin Timberlake to close the weekend event, billed as the Legends Of The Summer, but there was another huge name waiting in the wings - fresh from her headlining performance at Scotland's T in the Park festival on Saturday night (13Jul13). Rihanna teased her appearance with a backstage photo of herself posing outside Jay-Z's dressing room, which she posted on Twitter.com. And she returned to the micro-blogging site after the gig to rave about the London festival, writing, "London you were on one tonight!! One Love!!" Timberlake and Jay-Z, who headlined the Wireless Festival at the Queen Elizabeth Olympic Park on Friday (12Jul13) and Saturday (13Jul13), respectively, teaming up for brief collaborations on both nights, came together properly on Sunday and took it in turns to perform a string of hits after kicking off the set with a rendition of Holy Grail from the rapper's new album Magna Carta... Holy Grail. The Legends concluded the final day of the three-day festival, which also featured performances from will.i.am, A Tribe Called Quest, Nas and A$AP Rocky.