But it didn't take long to get close because their first day at work was taking dance lessons together.
"It's a great way to get to know a person," Lawrence told me at a special screening of the film at the Academy of Motion Picture Arts and Sciences in Beverly Hills. "You're instantly sweating and learning something together."
Cooper said he felt comfortable from the start.
"I remember I thought, OK, it's going to be all right because we are holding each other and we were both very vulnerable to this choreographed dance that we were going to have to do in three weeks in front of Robert De Niro. We [were] treading water together, helplessly treading water together."
Lawrence, who insists she's an "awful" dancer, went so far as to say that hitting the dance floor was harder than making the action-packed Hunger Games.
"If you miss a target, you still look cool because you're holding a bow and arrow," she said. "But when you mess up dancing you just look like an idiot."
Not to worry. Considering how much Oscar buzz the film is getting, it's obvious everything turned out just right.
"They were really beginners," director David O. Russell said (with a very big laugh!) about Cooper and Lawrence's initial dance moves. "But what they lacked in skill, they made up for in passion and willingness. They had a lot of willingness…They learned how to dance. They started out not knowing."