Doctor Who regeneration twist as Jodie Whittaker becomes David Tennant

After bidding a bittersweet farewell to companion Yaz (Mandip Gill), the Time Lord decided to leave the confines of the TARDIS and "take in one last sunrise", materialising on a clifftop.

With a smile on her face, Thirteen delivered her sign-off: "That's the only sad thing... I wanna know what happens next. Right then, Doctor whoever I'm about to be – tag, you're it!"

Sex Education star Ncuti Gatwa was announced as the next Doctor in May of this year, so fans would have been forgiven for expecting his face to emerge as the golden light of regeneration energy faded. Instead, they were greeted by a more familiar face, with the Doctor once again being played by David Tennant.

Tennant played the Tenth Doctor between 2005 and 2010 and while his return to the series as part of its own 60th anniversary festivities was also confirmed back in May, it was unclear until now how exactly he would be reintroduced.

In fact, Tennant himself had even stressed that Gatwa would be "the next Doctor Who" when pressed on the matter in an interview with The Times earlier this month.

But it appears there was some misdirection at play, with Tennant now apparently playing a new incarnation of the Doctor – albeit one who's revisiting an old face.

"I know these teeth," he says – a reference to the Tenth Doctor's first words ("New teeth... that's weird."), before then delivering Ten's classic "What? What?! WHAT?!" catchphrase.

Though this is the first time that Doctor Who has depicted this twist on regeneration on-screen, the idea of the Doctor assuming a face he's worn before is not unprecedented – fans will remember that the enigmatic Curator (Tom Baker), who appeared in the show's 50th anniversary special The Day of the Doctor, was heavily implied to be a future Doctor who had taken on a form similar to that of his previous fourth incarnation.

It's now unclear at what point Gatwa will make his Doctor Who debut, though he is expected to start filming on the series in November.

Before we meet an entirely new Doctor, though, we'll be adventuring through space and time with a Time Lord who's similar but different to the ever-popular Ten, with Catherine Tate also returning as companion Donna Noble under returning showrunner Russell T Davies.

Departing series boss Chris Chibnall had previously hinted at a jaw-dropping ending to The Power of the Doctor. "Even the tiny bit of the end just made me thrilled about and excited and desperate to see more about what comes next," he said.

Almost six decades in and it's certainly fair to say that Doctor Who hasn't lost its ability to deliver a killer cliffhanger...

Read more about Doctor Who:

• Doctor Who brings back classic Doctors for centenary special
• Doctor Who revisits old companions in touching scene
• Jo Martin makes Fugitive Doctor cameo in Doctor Who special
• Doctor Who's Sacha Dhawan: 'I'll never, ever forget playing the Master'
• Doctor Who’s Sacha Dhawan “overwhelmed” at getting to play the Doctor
• Doctor Who’s Sacha Dhawan would “love to come back” to face Ncuti Gatwa

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