The Doctor and The First Doctor in “The Doctor Falls”

No! [he fights off his regeneration] I will not change!

[in the distance] I will not change! I will not! No, no, no, no. The whole thing's ridiculous!

Hello! Is someone there?

Who is that?

I'm the Doctor.

[approaching] The Doctor? Oh, I don't think so. No, dear me, no. You may be a Doctor, but I am the Doctor. The original, you might say!