Circus Is A Song Performed By American Pop Singer Britney Spears. The Song Was Announced As The Second Single From Her Album Of The Same Name By Spears' Official Website On October 31 2008 And Peaked At #3 When It Debuted On The Billboard Hot 100 In Autumn Of 2008. It Went To #1 On The U.S. Mainstream Top 40 Chart In Winter Of 2009.