David Tennant has said he feels Doctor Who fans always expected him to be involved in the 50th anniversary episode of the show.
The actor, who played the 10th Doctor, told the BBC's Doctor Who blog what it was like to be involved in making TV history.
He said: "I think since I left, the expectation had been that I'd end up in this special, because there is a precedent for old Doctors coming back for a visit around the anniversary time. I was thrilled because it's a huge thing for Doctor Who and it's a huge thing for television in general."
Talking about the pressure involved, he said: "You're just trying to film the scenes the best you possibly can, so you sort of put aside the idea that you're making something that is a moment in television history. The pressure of that would sort of paralyse you."
David said that despite having to share the role with his successor Matt Smith, who is the 11th Time Lord, there was no rivalry during filming.
He said: "I think people almost expected Matt and me to be at loggerheads, but we've really enjoyed it. I guess when you've played a character for a long time you kind of feel like you know how they'll react in most situations.
"It's delicious to be handed a situation that's completely new and a character meeting a version of himself is not something that you come across in a lot of drama. So to get to play that with someone as talented and as quick and brilliant as Matt is nothing short of jolly good fun."