By Mark Savage
BBC News entertainment reporter
Rap star Jay-Z joined Rihanna on stage for two songs as she launched her new album, Rated R, in Brixton, London.
The Barbadian singer, 21, was playing her first show since she was assaulted by her ex-boyfriend, Chris Brown, in February this year.
She emerged on stage in an eye mask and studded leotard to perform a selection of new songs and hits like Take A Bow.
Jay-Z made his surprise appearance for the finale, performing his recent hit, Run This Town, and Rihanna's Umbrella.
Several members of the audience, made up of competition winners, held aloft umbrellas during the song in an unorthodox moment of crowd participation.
The 45-minute show kicked off with two songs from Rihanna's new album - Wait Your Turn and Russian Roulette.
Rihanna's new album will be released on 23 November
Slow-burning and dramatic, they set the tone for a concert where many of the star's hits were reinvented with distorted guitars and dark, pulsing synths.
The set-list included fan favourites such as Don't Stop The Music and Disturbia, while Rihanna was also joined by rapper Young Jeezy for Hard, a track which is set to be the second single from her new album.
Jay-Z, who signed the singer to Def Jam records, had previously appeared at his wife Beyonce's concert at the O2 on Sunday night, alongside Kanye West.
Star guests at Rihanna's show included Adele, Keisha Buchanan, Tinchy Stryder, Emma Bunton and Chipmunk.