70 years in the making, the Disney cartoon that's bigger than Potter

It is the most expensive animation ever made and the 50th work to be produced by Walt Disney Animation Studios. Now Tangled, a re-telling of the Rapunzel fairy tale, could knock the latest Harry Potter film off the top of the US box office.

The $260m (£165m) animation, to be released in Britain in January, retells the Brothers Grimm story using three-dimensional animation and an updated script. The Hollywood Reporter said yesterday that the film narrowly managed to unseat Harry Potter and the Deathly Hallows, Part 1, from the top spot at the US box office last weekend and predicts it could out-perform the Harry Potter film this weekend. The industry newspaper said that while the Harry Potter installment took $50m last weekend, Tangled, released a week later than Harry Potter last month, took $49m during the same period.

The secret of the movie's success, critics claim, is its polished updating of the traditional story. While the new film's titular character has the Grimm story's long hair, most of the other details have been changed. "It's a traditional fairy tale with a very engaging contemporary twist," said Justin Johnson, head of children's programming at the British Film Institute, which will be screening all of Disney's animations, including Tangled, next year. "It has a sassy heroine, who isn't grating, but is amusing, and it translates the classic animation feel of Disney's golden age in the 1940s and 1950s using all the computer-generated technology to make it very modern."

In the original fairytale, Rapunzel is imprisoned because of her parents, who sneak into a witch's garden and steal a magical flower.

In the Disney version, the witch imprisons the girl because she believes that the girl's long tresses somehow bring eternal youth. The new cartoon also has modern dialogue. "Sorry, Blondie," Rapunzel is told at one point, "I don't do back story."

Tangled is also the first Disney animated feature since 1997 with music by Alan Menken, who composed the music for the studio's Little Mermaid and Beauty and the Beast, which later transferred to Broadway. "This [film] is especially exciting because it was on the original list of Disney projects back in the 1940s," Roy Conli, Tangled's producer, said.

"The team back then were trying to figure out a way into the story. It's come on and off the shelf in the last 60 years and it took two brilliant directors, Nathan Greno and Byron Howard, to find a way into the story and give it a contemporary setting." US pundits predict that by the end of the week Harry Potter's gross takings will be in the region of $250m while those for Tangled will be about $100m.