The X Factor finalists tonight spoke of their delight at their charity single looking set to get to number one.
The four remaining acts - Misha B, Little Mix, Amelia Lily and Marcus Collins - spoke as they played a secret gig in central London.
The finalists have collaborated on a cover version of Wishing on a Star to raise money for Together for Short Lives, which provides support for children unlikely to reach adulthood, as well as their families.
The single also features the other finalists on the ITV1 show along with previous contestants JLS and One Direction.
The release has been outselling its nearest competitor Olly Murs' Dance With Me Tonight this week by more than two copies to one, according to the Official Charts Company.
Speaking ahead of their performance tonight, Jesy Nelson of four piece Little Mix, said: "It would be amazing if we got to number one. It would be an overwhelming feeling knowing that we're helping so many kids."
Her bandmate Perrie Edwards added: "It's such a good cause. When you meet these children you realise how privileged you are to have your health."
Speaking of being the girl band to have reached the furthest stage in any series of the X Factor, she added: "We are overwhelmed. We can't believe we've made it so far.
"We were favourite to go in the beginning and now we're here in the semi-final. It's just unbelievable."
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