The Jonas Brothers' London concert was absolutely bonkers on Monday night!
Not only were the tweens in attendance treated to a performance by the trio of siblings, but the boys surprised their fans when they brought out their British equivalent, McFly, for a duet on their song Star Girl.
London had a big concert on Sunday in celebration of their hosting the next Games in 2012. Over 100,000 people attended and the British Jonas Brothers, McFly, performed.
CLICK HERE to watch them performing Abba's The Winner Takes It All and their new single, Lies.