Doctor Who's 50th anniversary episode will be broadcast around the world at the same time to become the biggest ever global drama simulcast.
The 3D special - which will see Matt Smith make his penultimate appearance as the titular Time Lord - is expected to attract audiences of more than more than 100 million after being sold to 200 countries.
An insider told The Sun: "The 50th anniversary special is a massive deal for fans around the world who were petrified the secrets would leak online the moment it aired in Britain."
The episode will air at 8pm on BBC One on 23 November - exactly 50 years after it first started in 1963 - meaning fans in Sydney, Australia, will tune in to the programme at 6am the next day while viewers in Los Angeles, California, will be able to catch the Doctor in action at 12pm.
Smith will be joined in the episode by David Tennant, who portrayed the Tenth Doctor, as well as Jenna-Louise Coleman, seen in the most recent series as Clara Oswald, and Billie Piper, who played Rose Tyler. John Hurt will play a previously unseen incarnation of the Time Lord.