Live show to reveal new Doctor
The new star of Doctor Who will be unveiled live on television later amid tight security in a bid to prevent their identity leaking out.
Sources close to the show say only 10 people know the name of the new Doctor, who will replace Matt Smith, and they are using the codename Houdini to try and keep it a secret.
Bookmakers have suspended betting on The Thick Of It star Peter Capaldi taking the role, after his odds tumbled to 5/6 favourite with William Hill when they stopped taking bets on Friday.
The Scottish actor, famous for his role as foul-mouthed Malcolm Tucker in the political comedy, is a lifelong fan of the show and wrote a letter to the Radio Times about the Daleks when he was a teenager.
Plans for the half-hour show were kept secret with a repeat of Celebrity Mastermind put in listings in its place.
The Daily Mirror reported that the new Doctor will be sneaked into the studio in disguise to ensure their identity is kept secret.
The show will be presented by Zoe Ball and feature interviews with Smith and executive producer Steven Moffat as well as celebrity fans and some previous incarnations of the science-fiction hero.
Other names mentioned as possible contenders include Daniel Rigby, whose award-winning performance as Eric Morecambe in Eric and Ernie beat Smith to the best actor TV Bafta in 2011, and Cutting It star Ben Daniels.
BBC drama controller Ben Stephenson said: "We can't wait to unveil the next Doctor with everyone live on BBC1 on Sunday night. Amongst all the speculation and betting, there has been lots of fun and intrigue at work as we've been using the codename Houdini as a decoy.
"It's the biggest secret in showbiz, even those working with the new Doctor on other projects at the moment have no idea they are in the presence of the 12 incarnation."