David Tennant has said that viewers will be left heartbroken by the final "brilliant" plot twists as he bows out of Doctor Who.
Tennant, 38, who has been hailed by many as the best Doctor in the Time Lord's history, gave a hint about the big climax to the epic tale, which airs on BBC One on New Year's Day.
Tennant told BBC Breakfast: "Coming to the final episodes, you (think) will these live up to one's hopes for what that finale will be? And then you read the script - The Doctor's been told he's going to die, he knows he's going to die, so you get to play that new flavour with this character that you've got to know so well... suddenly you're playing a man who knows his end is coming."
The story, titled The End of Time, Part Two, sees the 10th Doctor facing the end of his life as the prophecy "He will knock four times" looms, while the terrifying plans of his nemesis the Master spin out of control.
Tennant said: "He's been told: 'He will knock four times' and you get the Master with these four beats in his head and you think, well, that's what that is. When you find out tomorrow (Friday) night what that really means - (it) just breaks your heart - it's brilliant."
He confessed to being "maybe a little" jealous of new Doctor Matt Smith because of the fantastic time he would be having in the job.
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