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Sam Bailey's Skyscraper has taken an early lead in the race to become 2013's official Christmas number one.

The X Factor winner's first single, a cover of a Demi Lovato track, is outselling its closest competitor, Happy by Pharrell Williams, by more than two copies to one.

Up to midnight on Monday nearly 45,000 copies had been downloaded.

Last year's winner James Arthur sold 187,000 copies of his debut single Impossible in its first 24 hours.

However, his single went to number one in the week before Christmas, with The Justice Collective's charity single He Ain't Heavy, He's My Brother topping the festive chart.

Pharrell's Happy, which is taken from the soundtrack to Despicable Me 2, is currently trailing Bailey by 27,000 copies in this year's Christmas chart race.

Leona Lewis' Christmas single, One More Sleep, remains steady at number three.

The former X Factor winner has just set a new Official Singles Chart record by becoming the first British female solo artist to score eight top five singles.

Meanwhile, after a Facebook campaign AC/DC's Highway To Hell looks set to become the second highest new entry of the week, debuting at number four.

Lily Allen completes the top five with her cover of Keane's Somewhere Only We Know - which was last Sunday's number one.

Sam Bailey won a recording contract after winning this year's X Factor and will also support Beyonce at one show on the UK leg of her world tour in February.

Simon Cowell's music company Syco is donating the profits of her CD and download sales to Great Ormond Street Hospital Children's Charity and Together For Short Lives.

The cut-off point for sales to be counted towards this year's Official Christmas number one is midnight on Saturday.

The Official Christmas Singles Chart Top 40 will then be unveiled on ´óÏó´«Ã½ Radio 1's Official Chart Show with Jameela Jamil and Scott Mills between 4 and 7pm on Sunday.

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