Watch: Octavia Spencer and Will Ferrell on singing in Spirited
The film is a unique spin on A Christmas Carol and imagines the spirits responsible for visiting Scrooge as employees of a company, which picks a loathsome individual to redeem each year.
Ferrell's Ghost of Christmas Present, on the brink of retirement, decides to challenge himself by taking on the 'unredeemable' marketing man Clint Briggs (Ryan Reynolds).
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The 55-year-old comedy star told Yahoo UK that, despite some singing experience in Eurovision Song Contest: The Story of Fire Saga, he had some fears taking on the role.
"It was kind of slightly daunting going into it and then, the more you scratch the surface, it becomes three times as daunting," said Ferrell.
He added: "It's like 'oh no, wow, this is gonna be a lot'. But it was too late. We had already signed the contract."
Reynolds' slick scumbag Clint pushes back against the ghosts, while Present begins a flirtation with his target's morally conflicted right-hand woman Kimberly.
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Kimberly is played by Spencer, who said that performing with the fully committed Ferrell helped her to feel more comfortable about showing off her own voice.
"I won't be known as a singer after this either," she said, adding that "you have to commit" to giving the singing both barrels.
Spencer added: "But here's the thing. I actually felt better about the singing when we started singing together because it didn't feel as daunting.
"I was like: 'Wow, Will is really good. I just need to play opposite him'. So it made it a lot more fun for me when we started working together."
Ferrell agreed that commitment is key, adding: "There's no half-speed. You have to really go for it and find that confidence. We were lucky that we worked with great people to help us get there."
Spencer said the chance to reinvigorate the story of A Christmas Carol after a century of countless adaptations for film and TV was a huge part of what attracted her to the job.
The 52-year-old said: "The fact we were getting to see it from a different perspective and make it fresh and new was something I saw as exciting. It was definitely an adventure, especially with Ryan and Will and the amazing cast that we had.
"The singing and dancing was daunting, but all the elements combined and I felt like we made a really delicious soup. And who doesn't love soup at Christmas?"
Directed by Ferrell's Daddy's Home filmmaker Sean Anders, Spirited also stars Sunita Mani, Patrick Page and the voice of Tracy Morgan.
Spirited is available to stream via Apple TV+ from 18 November.
Watch: Trailer for Spirited