US hip-hop star Jay-Z was reunited with his protege Rihanna at BBC Radio 1's Hackney Weekend tonight.
The Talk That Talk singer, who is headlining the music festival tomorrow, made a surprise appearance with the rapper - her mentor - on their hit Run This Town.
Jay-Z, whose real name is Shawn Carter, topped the star-studded bill at the Hackney marshes in east London, where other star performers included American musicians like Nicki Minaj, Will.i.am and Jack White as well as home-grown talent such as Leona Lewis, Example, Rizzle Kicks, Ed Sheeran and Michael Kiwanuka.
Closing the day's event, Jay-Z performed past hits like 99 Problems, Bonnie & Clyde and Girls, Girls, Girls.
Leona Lewis, who grew up in Hackney, earlier spoke of her pride at performing on her home ground to open the BBC's biggest free live event.
Some 50,000 attended the gig today, with another 50,000 expected to be present tomorrow.
The light showers failed to dampen the crowds' spirits.
Rihanna, Plan B and Florence + The Machine are among the acts performing tomorrow.