He said: "I was nervous to work with David because I knew he was going to be so demanding - I've seen all his movies and there's really not one bad performance.
"But it was an incredible experience and he's become a dear friend."
Bradley is particularly enjoying his career at the moment because he is doing his best to challenge himself professionally.
He told Total Film: "Lately I've been doing things that really scare me. I've taken on projects that are compelling and challenging."
One such challenge was on 'The Words' - in which he plays a struggling writer who obtains overnight success after stealing another author's work - which was directed by his old friends Brian Klugman and Lee Sternthal and also stars Jeremy Irons, Dennis Quaid, Ben Barnes and Zoe Saldana.