The singer was the headliner for the first night of the festival in London, and his 'Suit & Tie' collaborator joined him for a live rendition of their hit.
Justin's wife Jessica Biel was joined by the likes of Snoop Lion, Rita Ora, Frank Ocean and magician Dynamo as she watched her husband go through an exciting performance seeing him play guitar and piano during the set.
After teasing the fans at the Queen Elizabeth Olympic Park, the star debuted his new single 'Take Back The Night'.
He said: ''Can I play something new London? Like something new new.''
After his impromptu duet, Justin closed his show with a rendition of 'SexyBack'.
Tonight (13.07.13), Jay-Z will return for his own headlining set before the pair will combine for a full performance on Sunday night.
They will also join forces later this year for the 'Legends of the Summer' stadium tour - for which Jay-Z has hired a ''cigar expert''.
An insider previously revealed: ''Jay met this cigar expert at a friend's private party recently. He had been hired to roll cigars for guests in a smoking room.
''They were chatting for ages about the origins of tobacco and all the different types and then Jay-Z offered to have him on board for the tour dates.''
In 1947, Dalton (Bryan Cranston) is the film industry's top-paid screenwriter, so of course the House Un-American Activities Commission goes after...
Seth Grahame-Smith's Pride and Prejudice and Zombies graphic novel has been made into a film.
Sir Elton's new album, 'Wonderful Crazy Night', came out the next day.
The video for 'Hymn For the Weekend' was filmed in Mumbai, India.
Three more seasons to go for this adored comedy.
LeBlanc was announced as one of Chris Evans' co-hosts on the brand new 'Top Gear' on Thursday.
New York trio Fun Lovin' Criminals first made an impact back in 1996 with the release of their since acclaimed debut LP Come Find Yourself.
This lively romp is entertaining enough to amuse the audience even when it veers off the rails.