Paul Dano "lucked out" when he cast Carey Mulligan in 'Wildlife'.
The 'Swiss Army Man' actor has made his directorial debut with the drama and was impressed with how the 33-year-old actress tackled the role of troubled housewife Jeanette as anyone else could have caused the film to "fall apart".
He said: "I remember saying to myself, Gosh!.
"Carey's just so sharp, her intent is so clear even though the character is so complicated. With a mushy actor, that would have fallen apart. I lucked out."
When it comes to her own career, the 'Great Gatsby' actress - who has two children with husband Marcus Mumford - just wants to challenge herself with a varied body of work.
She told W magazine: "You do something well and people want you to just repeat that thing over and over.
"After 'An Education', I got a lot of offers to play quirky girls going through big life changes, and I didn't want to do that.
"'Suffragette' was quite message-y, and I don't really want to be in message movies anymore. It's really just not wanting to take on things I could competently do without much work. It doesn't seem worth it."
Carey credits her 'Pride and Prejudice' co-star Keira Knightley with teaching her a lot about how to behave on set because despite her fame, the 33-year-old star was always "lovely".
She said: "Keira had been in 'Pirates of the Caribbean', and she was unbelievably famous. I didn't need to put this into practice until years later, but she was the model of how to be a leading actress on set.
"She was brilliant, but she was also so kind and so sweet, and it sort of removed the possibility in the future of there being any excuse for being anything but lovely.
"I was watching people not only to learn how to act, but also to learn how to be. I did that for years."