Comic Frank Skinner has said he has been worried his guest performance on tonight's night's edition of Doctor Who may not be up to scratch.
The Absolute Radio presenter said he was so excited to be asked to be in the BBC1 show that he did not consider whether he would be any good in the role.
Skinner plays a character called Perkins in the show, set aboard an Orient Express-style craft which travels through space.
He said: "Since I did Doctor Who I've spent many an hour fretting about my performance, whether it was good enough.
"Now we get closer I'm thinking 'oh I couldn't care - I'm in it'. So my excitement has overtaken my personal dignity. That hasn't happened for years."
He said he was hoping to have a celebration with his loved ones when the show is screened.
"I'm thinking of getting one of those family gatherings, you know those ones you hear about when everyone gathers round the telly and they have been cut out of the episode completely. I'm thinking of having one of those."