When did the network announce that the show would feature Tennant and Piper again ?
In " The Day of the Doctor " , Smith and Coleman star alongside David Tennant and Billie Piper ; Tennant reprised his role as the Tenth Doctor , while Piper , although credited as playing Rose Tyler , in fact portrays a manifestation of " The Moment " , a Gallifreyan super-weapon , that has taken on Rose 's form .