Overview:The 10 remaining acts battle it out to win the public's votes and stay in the competition. Today's theme is Big Band, which means the contestants must face the challenge of singing with a full orchestra. How will they get on? Judges Simon Cowell, Cheryl Cole, Dannii Minogue and Louis Walsh will be keen to support the acts they are mentoring, and host Dermot O'Leary is on hand to keep everyone going as the tension mounts.