The Hillsborough charity single, 'He Ain't Heavy, He's My Brother', has sold more than 100,000 copies since its release on Monday and currently leads the race to be Christmas No.1.
As of midnight on Tuesday, the Justice Collective's cover of the Hollies track had been purchased 109,700 times, earning an advantage over closest rival James Arthur - whose song 'Impossible' has sold 106,300.
Martin Talbot, managing director of the Official Charts Company, said:"This really is the closest No.1 battle we can remember.
"Even closer than the legendary 2009 battle between Rage Against The Machine and Joe McElderry. The poll concludes at midnight on Saturday, so there is a long way to go yet - but this one looks like going down to the wire."
Physical copies are available at all good music retailers and a digital version can be downloaded via iTunes, HMV, 7 Digital and Amazon.
The single will soon be available to buy from Liverpool FC official club stores. The club is not a chart-registered company and so sales of the song have been prioritised to other outlets for the time being, in order for the single to stand a better chance of reaching No.1 in the Christmas charts.
You can also purchase the track by texting the word 'Justice' to 80010 from your mobile phone in the UK (£1 + standard network rate). From the Republic of Ireland text 'Justice' to 53600 if you would like to order a copy (€1.50 + standard network rate).
Please note that due to the very high demand, texts to download may suffer a delay of a few hours.