Alexandra Burke won the X factor less than 48 hours ago but already it is clear that she is sure to scoop the coveted Christmas Number One single spot.

Alexandra’s version of the song was available for pre-order from last week and became available to download at midnight on Saturday night.

HMV confirmed the single was its fastest-ever selling download and is predicting this year’s Christmas number 1 is now a certainty.

Gennaro Castaldo from HMV said: “Hallelujah promises to be the biggest X Factor release yet, and the chances are that Alexandra will have the Christmas No 1 single in the bag even before her CD single officially hits the stores in midweek.

“Alexandra’s biggest challenge for the festive top spot is likely to come from Peter Kay’s alter-ego Geraldine McQueen, but the reality is that while he may sell in the tens of thousands, Alexandra will sell in the hundreds of thousands – it’s really all about the race for the No 2 spot now.”

The bookies are also backing Burke to hit the spot, and odds of Alexandra reaching number one this week have been set at 1/8 by Ladbrokes. Ladbrokes spokesman Nick Weinberg said: “It’s as close to a certainty as you’re likely to find.”