Published Monday, 10 September 2012
The Umbrella hitmaker and the rapper teamed up to wow the crowd at the event's closing ceremony with a rendition of their track Run This Town.
And the pop royalty proved they are inseparable by heading to upmarket London nightspot the Arts Club following the show, where they met up with Gaga, who is in the UK touring her Born This Way Ball gigs.
Gaga posed for pictures outside the venue wearing a tiara and a wedding dress-style gown, but her pals were far less glamorous - Rihanna was sporting a garish orange T-shirt and matching baggy trousers, and Jay-Z kept it simple in jeans and a hoodie.