||Nine star Penelope Cruz said she thought the choreography was 'impossible' on the first day of rehearsals for the flick.
The 35-year-old actress stars alongside Kate Hudson, Nicole Kidman, Fergie, Sophia Loren, Marion Cotillard and Judi Dench in the hit movie.
Cruz plays the role of Daniel Day Lewis's mistress Carla and her big dance number involves rope and satin sheets.
She told the UK's Sunday Times Culture magazine: "When I saw the choreography the first day, I thought it was almost impossible to be able to get to dance and sing like that, and do the whole number at once without stopping.
"It was three months of rehearsing for that number, every day a little more, a little more. The day that you get to run the number without stopping, you feel like you are flying - such a beautiful feeling."
Cruz added that she really enjoyed her first professional singing role and practised hard for the part. She said: "I'm a very big fan of music. I sing at home in my karaoke machine and in the shower, but it was the first time professionally. I loved it."