But the teenager got 47 per cent of the public vote, proving that you don't always agree with the teachers!
Katie, who's never hidden the fact that she's never sung pop songs before, wowed the crowd with her cover of eighties hit Perfect by Fairground Attraction.
Malachi impressed everyone with his version of David Gray's Babylon.
But Marli's performance of old time classic, Tracks of My Tears, wasn't enough to keep her in.
Nigel and Ainslie