The princess of pop jetted across the pond to perform her "Circus" -- and had a musical surprise for her fans!

For her European tour, Brit decided to sing and shake it to remixes of some of her hottest tunes, including "Baby One More Time," "Do Something," "Piece of Me," "Ooh Ooh Baby," "Radar," "I'm a Slave 4 U" and "Womanizer."

Spears twittered after performing her first gig in the U.K., "Just wrapped my first show in London. I love all the remixed tracks and new costumes!"

Britney will remain in Great Britain for eight more shows before taking the "Circus" on the road to Dublin for a concert on June 19.