It's the second big film, said Audrey, which will prove if I was really worthy of the first. That second film was Sabrina, a modern Cinderella story set in Long Island, Audrey playing the chauffer's daughter turned sophisticated Parisienne who falls in love with, first the youngest, then the eldest son of her father's millionaire employer, the love interests played by William Holden and Humphrey Bogart respectively. Bogart was notoriously difficult on set, hated Holden and even complained about Audrey, grumbling to Clifton Webb She's okay... if you like to do thirty-six takes. Director Billy Wilder, however, had such a high opinion of the young star that he consulted her on everything, becoming a great mentor and friend.
On top of the on-set animosity between the leading men, the script had become a chaos of re-writes. According to Wilder, the original screenplay had been written for Cary Grant rather than Bogart, so Wilder and screenwriter Ernest Lehman stayed up most nights getting the pages ready for the next day. This only increased the tension on set, as a grumpy Bogart lost his temper over the script. Reportedly Wilder even asked Audrey to stall the production by pretending to be ill, giving him more time to finish writing the next scene. It is no surprise, therefore, that Audrey's working script is incomplete, lacking the latter portion of the film. The stack of loose pages in lot 40 expose the ongoing re-writes, showing earlier versions of the dialogue.
Despite the production troubles, the film was a success, and Audrey sparkled. As part of the plot, Wilder wanted Sabrina dressed in Parisian couture on her return from France and sent Audrey to Paris to pick out her wardrobe. Thus began a lifelong association between Audrey and Hubert de Givenchy. Givenchy remembered She knew exactly what she wanted... What I invented for her eventually became a style, so popular that I named it "decollete Sabrina."