What A Wonderful World, Katie Melua's charity duet with the late Eva Cassidy, will top the UK singles chart this weekend, midweek sales data suggests.
The original Louis Armstrong song was first released in 1967
According to Music Week, their version of the Louis Armstrong song will knock Bleeding Love by Leona Lewis off the top spot after seven straight weeks.
Profits from the sale of the single - only available via supermarket Tesco - will go to the British Red Cross.
Cassidy, a heroine of Melua's, died of cancer in 1996 at the age of 33.
Bookmakers Ladbrokes make the single 5/1 to be Christmas number one, just behind Leona Lewis.
However, the eventual winner of The X Factor remains the overwhelming favourite to top the chart.
Lewis's debut record Spirit is expected to remain top of the album chart according to midweek data.
Meanwhile, music chain HMV report a significant spike in sales of Led Zeppelin records in the wake of the rock band's reunion concert on Monday.
According to spokesman Genarro Castaldo, sales of the group's back catalogue are five times their normal level.
Led Zeppelin's greatest hits collection Mothership was the store's best-selling artist album on Tuesday, he added.