Russell T Davies appeared on BBC Radio 5 this morning and gave us some hints about what we can look forward to in this year's Christmas special, The Next Doctor.
"The big question, how can it be the next Doctor?" the executive producer said. "How can the Tenth Doctor be meeting the next Doctor? And it's not just the next Doctor you get to see, you get to see some old ones aswell, which is rather exciting. So, it's a 'Doctor-fest', in a way.
"It's believed that some previous incarnations of the Doctor will be seen in flashback sequences.
Davies continued: "But, as to how the two of them can be together, and the very sad, Christmassy story behind that is what you've got to watch on Christmas Day for!"
Well, we'll definitely be watching!The Next Doctor will air on BBC One on Christmas Day at 6pm.