The X Factor finalists have spoken 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 the Talk Talk gig, Jesy Nelson of 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."
Soul singer Misha B, who has been mentored on the show by Kelly Rowland, said she was also thrilled that the single was selling so well.
She said of being a contestant on the show: "It's just an amazing experience. Like I was just saying to the other guys, I still can't believe I'm here."
Amelia Lily, who was voted back into the series following Frankie Cocozza's departure, said she had been busy during the time she was out of the competition: "I've been gigging all around the country and I've still been performing."
Marcus Collins, the only remaining male contestant, said he and the other acts had received support from Simon Cowell: "We've spoken to him as a group and he's given us some really good constructive criticism and ways of improving our performance."