The Dark Knight director Christopher Nolan calls the casting of Academy Award nominee Robert Downey Jr. as Tony Stark aka Iron Man in the MCU nothing less than “one of the greatest casting decisions in the history of movies.” Appearing on the Happy Sad Confused podcast, Nolan, who works alongside Downey Jr. for the first time in the biographical thriller Oppenheimer, heaps praise on the Marvel star and the decision to put him at the center of the franchise.

“When [Jon] Favreau had the insight to cast him as Iron Man, I mean that’s … one of the greatest casting decisions in the history of movies. And you look at what that did and where that went with everything. And I think that was Jon just knowing what an incredible actor, what incredible potential it was from Downey. And then the movie star charisma, that wonderful charisma comes into play.”

The influence that Downey Jr. has had on both the MCU and the pages of Marvel Comics is evident, with the MCU now a multi-billion-dollar franchise off the back of 2008’s Iron Man and the character being changed to more resemble the actor’s portrayal in the comics. However, while his success in the world of Marvel is clear, Nolan did have to request that Downey Jr. make some changes when starring in Oppenheimer…

“What was cool about getting to work with Downey on this project was to be able to go to him and say, ‘Okay put that charisma, put that movie star thing to one side for a second, and just lose yourself in this real-life human being who is so complex and has such an incredible part to play in Oppenheimer’s story. And to watch him just sort of go back to that geniuses as an actor, just finding the truth in another human being and presenting it, and the things he does in the film, I think a lot of his fan base is going to be extremely surprised. It’s really cool to see somebody who’s achieved such greatness as a movie star, that pivot completely and stretch themselves in a way that a lot of people haven’t seen him do.”

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Robert Downey Jr. Calls Oppenheimer the Best Movie He’s Ever Been In
Courtesy of Universal Pictures

The respect between Christopher Nolan and Robert Downey Jr. is undeniable, with this being far from the first time that the actor and the director have heaped praise upon each other. Recently, Downey Jr. teased the sheer quality of Oppenheimer saying, “Just going to flat out say it: This is the best film I’ve ever been in. And I cannot wait for you all to experience it.”

And it certainly could be, if the reviews are to be believed. Written and directed by Christopher Nolan, and based on the Pulitzer Prize-winning book American Prometheus: The Triumph and Tragedy of J. Robert Oppenheimer by Kai Bird and the late Martin J. Sherwin, Oppenheimer chronicles the life of the enigmatic man who must risk destroying the world in order to save it.

Led by Cillian Murphy as J. Robert Oppenheimer, the project has amassed one of the most star-studded casts in cinematic history and includes Emily Blunt, Matt Damon, Robert Downey, Jr., Florence Pugh, Benny Safdie, Josh Hartnett, Rami Malek, Kenneth Branagh, Dane DeHaan, David Krumholtz, Alden Ehrenreich, Matthew Modine, Jack Quaid, David Dastmalchian, Jason Clarke, Josh Peck, Alex Wolff, Casey Affleck, Gary Oldman and more.

Oppenheimer is in theaters from today.