X Factor winner James Arthur is set to lose his spot at number one this weekend, missing the Christmas number one.
James' winner's single Impossible has already topped the charts, so holding on to number one for a second week would only been a bonus.
The song, a cover of Shontelle's 2010 track, has so far sold over 100,000 copies this week, adding to its impressive 490,000 tally from its first week on sale.
However the song is now some 14,000 copies behind the Justice Collective's Hillsborough charity track, a cover of He Ain't Heavy featuring stars include X Factor's own Rebecca Ferguson.
The charity single is now in top of the charts in the the latest midweek data, having overtaken James who as leading the battle at the start of the week.
But with just 14,000 copies between the two songs and still a few days of the week to go, it's sure to be a close outcome.
"This really is the closest battle we can remember - even closer than the 2009 battle between Rage Against The Machine and Joe McElderry," managing director of the Offical Charts Company, Martin Talbot said.
"The poll concludes at midnight on Saturday (22 December), so there is a long way to go - but this one looks like going down to the wire."
The Xmas number one will be officially revealed on Sunday evening live on BBC Radio 1.