Matt Smith has joked that locking lips with Jenna-Louise Coleman wasn't easy.
The star, who portrays the Time Lord, gets to kiss his new Doctor Who sidekick in the upcoming Christmas special.
"I like our kiss - that was fun. Even though it was hell to do," he told The Sun.
Jenna, who plays the Doctor's new assistant Clara Oswin in the show, added: "We did a couple of versions. One was like a swoop."
Matt also revealed that the festive episode is set in the 1800s and will feature Richard E Grant and Sir Ian McKellen.
"We have killer snowmen and killer snow and we've got Richard E Grant - who was born to be a Who villain! He's a wonderful guy," he told This Morning.
"And most importantly we get to meet the new companion Clara, played by Jenna Louise Coleman, who has started thrillingly - she has done brilliant work, very detailed, she's very hard working and she's just a delight."