Ahead of the Fourth Doctor's regeneration in "Logopolis," he encounters his own Watcher, and was able to speak with them.

However, as well as the addition of the Fourth Doctor’s face ... is given the task of looking after the Doctor during his recovery from his regeneration. At the close of the story, Harry ...

The writers for the regeneration scene weren’t doing anything ... The Geronimo line is now just as memorable as the Fourth Doctor's iconic scarf and really helped to pin Smith’s time as ...

However, this is the first and only time in which the circumstances of the Doctor's regeneration at the start of a series remain unexplained. This is only the second time in which the Doctor ...