For many people, the biggest day of December begins the morning after Santa pops down the chimney.
But, for an array of pop stars, Facebook campaigners, charity singles and chart watchers, attention is focused on another day - the day the Christmas Number One is confirmed.
The race for the Christmas Number One is as festive as turkey and mulled wine. And this year, with the big day falling on December 22 (and BBC Radio 1's counting down the Top 40 from 4-7pm), it is likely to be as spicy a race as we have seen for some time.
The past five years have seen a string of highly charged moments - the Military Wives singing in 2011 for their absent loved ones, the Justice Collective performing last year in memory of the 96 fans killed at Hillsborough in 1989, Alexandra Burke pipping Jeff Buckley as two versions of the same song finished at one and two for the first time in 2010. And, of course, in 2009 Essex-based husband and wife duo Jon & Tracy Morter launched a Facebook campaign which drove Rage AgainstThe Machine to pip wholesome Joe McElderry to the Number One spot.
Of course, the excitement surrounding the Christmas Number One is nothing new. As long ago as the late 50s, it quickly became apparent that being the nation's favourite single in the week before Christmas was often the year's biggest seller too - and turned it into a highly coveted honour. Al Martino had the very first Christmas Number One in 1952 with Here In My Heart, Dickie Valentine's Christmas Alphabet was the first festive song in 1955, Cliff scored his first (with The Shadows) in 1960, and The Beatles scored four in five years during the 60s.
Then, in the Seventies, novelty Christmas tunes took the festive Number One1 honour to new levels, thanks to the likes of Slade's Merry Xmas Everybody, Mud's Lonely This Christmas and Johnny Mathis' When A Child Is Born. Novelty has remained a crucial part of the formula ever since - from St Winifred's School Choir and The Flying Pickets in the 80s, through to Mr Blobby and Bob The Builder in the 90s and 00s. And then came X Factor's domination and the Rage Against The Machine fightback.
Our fascination with the festive chart-topper continues to this day. The fact that more singles are bought than at any other time in history - 189m were sold in 2012, twice as many as the pre-digital high point of 89m in 1979 - ensures that securing the biggest seller in the biggest week of the year is a prize worth having, for artists and labels alike.
Plus, of course, the Official Singles Chart has evolved into one of the most high profile public polls we have - whether you are voting for One Direction over the Wanted or want to make a statement in the aftermath of a former prime minister's death.
The public interest in such battles is understandable - and was ignited by that incredible battle of 2009. As the sales week started, few believed the Rage campaign had a chance, but when sales reports came through at the start of the week, Rage were ahead and it was clear that an unlikely victory was possible. By the end of the Friday, Rage's Killing In The Name was neck and neck with The Climb - the X Factor single gaining fast. But, over the weekend, the Rage campaign found some new momentum, eventually running out as winners, 503,000 to 450,000.
The continuing influence of that campaign is all too apparent this year - with X Factor in a head-to-head for the first time in three years.
For the past two years, the X Factor winner's debut single has been released a week before the Christmas race, and has not quite maintained the momentum required in this most competitive of weeks. This year, X Factor is back in the game - the winner's first single will be released this Sunday evening (December 15), pushing it straight into the heat of battle.
And it will have a fight on its hands, with several Facebook campaigns bidding to replicate the Rage success of 2009. The leading contender is AC/DC's Highway To Hell, backed by a campaign with 150,000-plus fans as the race was due to start and which looked to have the necessary momentum to mount a serious challenge.
There are other (more conventional) contenders too, including Leona Lewis's own Christmas tune One More Sleep, Slade's Everyday (from the Google Nexus ad campaign), Lily Allen's John Lewis ad theme Somewhere Only We Know, Orbital's Christmas Chime and so on. Click here for the definitive list of 2013's Christmas Number One contenders.
The beauty of every Number One race (of course) is that anything can happen. At Christmas, it can be even more unpredictable - as Rage Against The Machine proved four years ago. Who's going to ride a one-horse open sleigh all the way to the snow-capped summit of the Official Singles Chart this Christmas week? Not even Santa can tell you that one - it's all down to the record-buying public.
Let battle commence.
The festive Top 40 will be counted down by Scott Mills and Jameela Jamil on BBC Radio 1's Official Chart Show from 4-7pm on Sunday 22 December, with the full Official Singles Chart Top 100 revealed on OfficialCharts.com at 7pm.
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