The Sing-Off - Contestants singing opening number of the finale

It's a very merry finale as the judges - and a slew of special guests - join the contestants on stage and the Season 4 winner is announced.

The Sing-Off - Ben Folds, Jewel, Shawn Stockman

The judges take control of the competition and select the songs for the four remaining groups.

The Sing-Off - Contestants singing "I've Had the Time of My Life"

The six remaining groups bring out the popcorn for big screen hits.

The Sing-Off - Contestants singing The Who's "My Generation"

Ben Folds mentors the groups as they take on hits that span the decades.

The eight remaining groups sing their favorite #1 hits to win over the judges.

The nine remaining groups pump up the jams with party anthems.

Ten talented a capella groups compete to impress the judges by singing their signature songs in The Sing-Off's Season 4 premiere.