Writer-director Christopher Nolan showered his Oppenheimer star Robert Downey Jr. with praise on The Late Show. While hailing the actor’s charismatic performance as Tony Stark in Iron Man, Nolan said that Downey Jr. is extremely generous to his co-actors. Nolan said, “When he’s in a scene with other people, he’s making sure that they are all doing their best and are all able to bring their best to the table.”

Downey Jr. is considered the frontrunner to win the Best Supporting Actor Oscar this year for his Lewis Strauss portrayal in Nolan’s Oppenheimer. Perhaps realizing that Downey Jr. is due praise further for that performance, Nolan focused more on Iron Man instead. He called the choice of Downey Jr. for the superhero role “one of the most consequential casting decisions that’s ever been made in the history of the movie business.”

Nolan said that he always wished to collaborate with Downey Jr., but there were times when things could not quite work out between the two. For instance, Downey Jr. pitched himself to Nolan for the role of Scarecrow in Batman Begins, which eventually went to his Oppenheimer co-star, Cillian Murphy.