The charity single - titled 'He Ain't Heavy, He's My Brother' - has been released to raise money for the families affected by the Hillsborough disaster.
The track is currently 23,000 copies ahead of its nearest rival, which is X Factor champion James Arthur and his winner's single 'Impossible'.
"The momentum is in favour of the Justice Collective, who now have a decent lead, having sold around 15% more than James Arthur at this point," said The Official Charts Company's managing director Martin Talbot.
"But they have opened up their lead in just two days - it could easily be closed over the next two days."
He added: "The Justice Collective are favourites right now - but their lead is not unbridgeable by any means. With two days of sales left to be counted, it is all to play for."
The final chart placings for the Christmas number one 2012 will be announced on Sunday (December 23).
Watch the music video for The Justice Collective's 'He Ain't Heavy, He's My Brother' below: