The final four groups take the stage for the final time before America votes on a winner with a massive mash up opening performance of The Who's Baba O'Reilly, The Verve's Bittersweet Symphony, Katy Perry's Last Friday Night (T.G.I.F.) and Gwen Stefani's Hollaback Girl. Later they take on mashing two hit songs together before performing a song of the judges' choice. One more group is sent home, leaving the final vote for a cappella champion to America.
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