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Britney Spears was joined on stage by Jedward during the second of her two gigs at London's O2 Arena.
The former X Factor twins made an appearance during a dance routine with Britney before joining her backstage after the gig.
Jedward – real names John and Edward Grimes – had been teasing their fans about their appearance throughout the day on Twitter.
They wrote: "We are gonna get to meet Britney spears. it gonna be the Biggest Moment of our Life! And the biggest Moment for Jedward Fans."
After arriving at the venue and heading backstage, they added: "we are backstage! This the most coolest thing eveeeeeeer!
"It's craZy we are gonna be breathing the same air! It's Britney Air! JEDWARDLoveBRITNEY #JEDWARDmeetingBRITNEY"
Britney's second gig at the O2 Arena again saw her perform songs from her latest album 'Femme Fatale', as well as hits like 'Toxic' and 'I'm A Slave 4 U'.
Watch a video of Jedward joining Britney on stage below.