|The Sing-Off Format|
|Description||A twist allowing the Bottom 2 groups to battle, in which the judges decide their fate|
As a new addition to the fourth season, the Ultimate Sing-Off was introduced, and occurs as follows: the bottom 2 groups are asked to perform together at the end of the show one final time. Although they learn the song ahead of time, and practice it with other groups, they have only a few minutes to rehearse with the opposing group. The groups sing the same song, alternating verses, until the end, where they sing together. The judges then must decide which group to keep, and which will be eliminated.
|Season||Episode||Competitor 1||Song||Competitor 2||Result|
|4||The Sing Off is Back!|
|"Bye Bye Bye"|