Sunday's results show saw a double elimination and Kiera was the first act to be told she would be going home after receiving the fewest votes.
Kiera, who was mentored by Rita Ora, put a twist on Mark Morrison's 'Return of the Mack', but it wasn't enough to keep her in the competition.
Next, hosts Caroline Flack and Olly Murs revealed that Seann and Mason Noise faced the sing-off. The boys, who are both mentored by Nick Grimshaw, had to fight for their place on the show.
Mason sang 'End Of The Road' while Sean sang 'A Song For You', and it was clear that the judges - who all admitted they were "shocked" with the bottom two - were struggling to make a decision.
Simon Cowell and Cheryl Fernandez-Versini chose to send home Mason, but Rita chose to send home Seann. Stuck between two of his acts, Nick decided he wanted to bring it to deadlock so that the decision would go back to the pubic vote.
Therefore, Nick chose to send home Seann. Caroline and Olly then read out the results from the public vote, revealing that the act with the fewest votes was indeed Seann.
Last week saw Bupsi Brown and Alien Uncovered eliminated from the competition.
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X Factor's most shocking moments: