Doctor Who's Christmas Day episode The Husbands Of River Song could be the least-watched seasonal special since the show was revived in 2005.
Last year's Christmas special, starring Peter Capaldi as the Time Lord and Nick Frost as Santa Claus, is the lowest to date.
It drew an overnight average of 6.3 million viewers in the ratings, according to the Broadcasters' Audience Research Board (Barb).
The BBC One programme increased to 8.3 million when consolidated figures, which take into account viewers watching by time-shifting and catch-up services, were released.
Voyage Of The Damned, Doctor Who's 2007 Christmas Day episode starring David Tennant as the Time Lord and pop star Kylie Minogue as waitress Astrid Peth, is unlikely to be beaten this year.
It was watched by an average of 12.4 million in the overnights and consolidated to 13.3 million viewers.
Voyage Of The Damned remains the highest rating Christmas Day episode of the sci-fi series since 2005.
Doctor Who's series nine finale Hell Bent, broadcast on December 5, averaged 4.5 million in the overnights. It consolidated to 6.2 million viewers.
Fans are hoping the early 5.15pm start for the Christmas Day special will not have a detrimental effect on the show's ratings.
Capaldi's Time Lord meets his wife River Song (played by Alex Kingston) for the first time since his regeneration.
The flirty chemistry between Capaldi and Kingston ignites this instalment as the duo take Doctor Who to rom-com territory.
Written by executive producer Steven Moffat, The Husbands Of River Song depicts Christmas Day on a remote human colony where the Doctor is hiding from Christmas carols and comedy antlers.
When a crashed spaceship calls on the Doctor for help, he finds himself recruited into River Song's squad and hurled into a frantic chase across the galaxy.
Comedians Matt Lucas of Little Britain fame and Greg Davies from The Inbetweeners are also on board, as Nardole and King Hydroflax respectively.
River Song made her first Doctor Who appearance opposite David Tennant in Silence In The Library in 2008.