X Factor winner James Arthur is leading the race for the Christmas number one - but by only a narrow margin.
Bookies had all but written off the chances of an X Factor festive chart-topper, and instead installed the Hillsborough charity single as the favourite.
But new figures released by the Official Charts Company showed Arthur's track Impossible was more than 3,000 copies ahead of the Justice Collective.
However, Arthur has an advantage as his 76,000 sales are across two days, while the rival song - a cover of The Hollies' He Ain't Heavy, He's My Brother - only went on sale on Monday.
Official Charts Company managing director Martin Talbot said the early lead was "exceptionally tight".
Last week Impossible became the fastest selling single of 2012, debuting at number one, with sales of more than 490,000 copies.
The Justice Collective track has an all-star cast with figures such as Sir Paul McCartney, Robbie Williams, Melanie C and Shane MacGowan.
Gennaro Castaldo of retailer HMV said: "The Justice Collective has the momentum that comes with a new release, and clearly a lot of people are passionate about its message, but James Arthur's really strong showing last week has probably surprised a few people, and with the Sunday he also has the benefit of an extra day's sales.
"For the moment the advantage is with James to remain at the top for a second week, but if the campaign behind Justice Collective keeps growing, as we think it will, He Ain't Heavy, He's My Brother still has a good chance of making it. It's going to be close-run thing."
Bookmaker William Hill has cut Arthur's odds from 11/2 to 2/1, but the Justice Collective continue to be favourites at 4/11. The chart will be announced on Sunday afternoon on Radio 1 by presenter Reggie Yates.