Season 4 of "Sherlock" commenced with a New Years Day broadcast in the UK, via parent channel BBC One, and the Benedict Cumberbatch detective mystery pulled in 8.1m viewers according to ratings estimates.
The modern-day update of Sir Arthur Conan Doyle's literary mastermind was the most popular show on UK television on January 1, according to overnight ratings seen by Deadline.
Season 4 of "Sherlock" returns after a three year absence.
Martin Freeman co-stars as Dr. John Watson, Amanda Abbington plays Mary Watson, co-creator appears as Sherlock Holmes' sibling Mycroft, Rupert Graves as Detective Inspector Lestrade, and Una Stubbs as Mrs. Hudson.
Rachel Talalay, who has also helmed episodes of "Supergirl," "Legends of Tomorrow," "Doctor Who," "The Flash" and "Ally McBeal," directed Season 4 Episode 1, "The Six Thatchers." Mark Gatiss and Steven Moffat (of "Doctor Who" fame) co-wrote.