There is nothing as powerful as 2 actors who have such lust and at times hatred of each other who enflamed the screen, I can only think of them and Humphrey Bogart and Lauren Bacall as being the ones who made such news, and had that kind of magnetism that seemed to compel, I loved reading about Richard Burton talking about playing Shakespeare and having Winston Churchill in the audience he kept hearing a rumbling until he noted that Winston was quoting the words of the wordsmith he knew them all by heart and couldn't be silent at the stage. I've known a lot of actors who told me that Burton wasn't much of an actor that he only had once voice his own. And I answered, he didn't need anyone else's voice than his own.
You out there directed them: no internal monogue reflecting on yourself, but got on to other people's spirits; pay attention to them, not yourself.