Rihanna made a surprise appearance at Yahoo! Wireless festival last night (14.07.13).

The 'Diamonds' hitmaker sent fans into a frenzy as she emerged on stage during Jay-Z and Justin Timberlake's joint headlining set to join Jay for a rendition of their hit, 'Run This Town'.

Although the singer headlined last year's Wireless festival, she was clearly content with just being part of the first ever Legends of the Summer dual headline show at the Queen Elizabeth Olympic Park in Stratford, London.

She wrote on Twitter after the performance: ''#Wireless #LegendzOfTheSummer #OpeningNight #Hov #JT #London you were on one tonight!! One Love!! (sic)''

The joint show was a preview of Jay and Justin's upcoming stadium tour of the US and fans were treated to a selection of each of their greatest hits, as well as opening and closing collaborations.

The duo kicked off their epic two-hour set with 'Holy Grail' -the lead track from Jay-Z's recently released album 'Magna Carta Holy Grail' - and later closed the show with Justin's hit song, 'Suit & Tie'.

Fans and stars alike convened at the main stage for the 'Legends of the Summer' show, with celebrities in attendance including Cheryl Cole, Jourdan Dunn and Misha B.

Other rousing performances on the final day of Wireless came from Will.i.am, who headlined the Pepsi Max stage, Rizzle Kicks, Big Sean, A$AP Rocky and Nas.