Reunited on-screen for the first time since Brokeback Mountain, the film sees Hathaway take on the role of a young woman with Parkinson's disease who falls in love with Gyllenhaal's Viagra salesman.
"Annie did the movie because she wanted to be in bed with me," the actor quipped to Sky News. "And I can't blame her."
He continued: "I was the 45th actor to be offered a role as no-one wanted to get naked with Anne but I needed the work. I felt sorry for her."
However, Hathaway hit back by poking fun at the 30-year-old for being self-obsessed.
"The thing is - working with Jake is hard because you have to wait for him to stop Googling himself for anything to be usable," she said.
> Zwick 'needed Gyllenhaal, Hathaway naked'