Matt Smith has said Jenna-Louise Coleman has given his Doctor Who alter-ego a new lease of life.
The actress stars in the latest series of the sci-fi show as the Doctor's new assistant, Clara.
Matt said of his co-star: "You'll see on screen she's absolutely brilliant and it's been a joy.
"I'm really proud of the work we've done and I think it's exciting for the character, he's got a new lease of life somehow."
He added: "Jenna's inventive, she works tirelessly hard. I like her, which is good because you've got to get on. And I'm really proud of what she's achieved and I'm pleased that it's gone so well for her because I think she's brilliant in it."
Doctor Who is coming up to its 50th anniversary, with a special episode shot in 3D.
Matt said of the anniversary: "It sort of does what it says on the tin. You won't be disappointed. I read it and I clapped at the end.
"It's epic and it's fast and I'm telling you nothing more; it's going to be the biggest, best, most inventive and most exciting year for the show, and I think this script delivers on all those points that you want it to for where the show is at this time. It's brilliant.
"We're upping the scale of everything; it's 3D - I won't say anything about the event but there's a bit more for your buck."
:: Doctor Who returns to BBC One on Saturday, March 30.