LOS ANGELES (Reuters) - If movie fans didn't know she was co-starring with Brad Pitt in "The Curious Case of Benjamin Button," they wouldn't recognize Cate Blanchett when the film opens with a close-up of her in a hospital bed, as a withered old woman.
The 39-year-old Australian actress, an Academy Award winner for her 2004 portrait of Katharine Hepburn ("The Aviator") and a two-time Oscar nominee last year as Queen Elizabeth ("Elizabeth: The Golden Age") and Bob Dylan ("I'm Not There"), disappears into another challenging role in "Benjamin Button," which opens Christmas Day.
She undergoes a striking transformation as the life of her character, Daisy, unfolds over eight decades, blossoming from a sprightly girl into a beautiful ballet dancer, then growing old while the love of her life inexplicably gets younger.
Blanchett says much of the credit for her metamorphosis goes to the "unbelievable" talent of makeup artists.
But the actress says her own performance was informed largely by experiences from her youth -- from childhood ballet lessons, to a close relationship with her grandmother and to her first job, at 14, serving meals in an old-age home.
"I would go in after school ... and the cook would have prepared the meal, and I had to dish it all up and take it around to the guys, have a little chat with them ... and I'd have to clean up after them and put everything away," she recounted in a recent interview.
In a memory that seemed to come straight from the movie, she recalled one of the home's matrons expressing consternation at having a patient move in to take the place of newly deceased resident so quickly that "the bed's still warm."
"For a 14-year-old to hear that, you think, 'Wow. That person's gone and someone else has come in?' Life really is a car park," she said.
The fleeting passage of time, and of lives come and gone, are major themes explored in "The Curious Case of Benjamin Button," an epic romantic drama about a man, played by Pitt, 45, who is born in his eighties and ages in reverse.
Abandoned as an infant on the doorstep of a New Orleans retirement home at the end of World War One, he is adopted by the home's caretaker and grows up in the company of old and dying residents who become his extended family.
In a transformation depicted with the help of computer graphic imagery, Benjamin spends much of his "elderly" boyhood in a wheelchair or on crutches, but gradually sheds the disabilities of advanced age as he reaches adulthood.
The rest of the film, nominated for five Golden Globe Awards and considered an Oscar contender, follows Benjamin as he sets off to find his way in the world.
The characters played by Pitt and Blanchett, who previously co-starred as a married couple in the 2006 film "Babel," first meet as children, and their lives intersect at various points through the movie as they head in opposite directions.
Directed by David Fincher ("Seven," "Fight Club," "Panic Room"), the film was adapted from a 1920s short fantasy written by F. Scott Fitzgerald. He in turn was inspired by a quote from Mark Twain: "Life would be infinitely happier if we could only be born at the age of 80 and gradually approach 18."
The screenplay is told in flashback from journal entries, letters and memories recounted from Daisy's hospital room, where she lays dying as Hurricane Katrina nears New Orleans.
Blanchett said her portrait of the aging Daisy was in part an homage to her grandmother, from whom she borrowed the habit of keeping a small handkerchief clasped in one hand.
"My grandmother had a huge influence on me, and I was around her as she got frailer and frailer," the actress said.
More difficult than creating a convincing older character on screen, Blanchett said, were the dance combinations she was required to learn and perform for the film.
Her own formal instruction in ballet ended in childhood, but Blanchett said she later studied movement in drama school.
For "Benjamin Button," Blanchett worked extensively with a choreographer and performed all her own dance scenes, though a stand-in was used for a couple of shots, including a sequence of really quick turns, she said.
Blanchett is hardly done with tough acting assignments.
She returns to the Australian stage in January for yet another gender reversal, and another portrait of an English monarch, in the title role of Shakespeare's "Richard II" for the Sydney Theater Co., where she began her career in 1992.
Editing by Bob Tourtellotte