The Bourne Legacy director Tony Gilroy has revealed it was "red alert" when he discovered Jeremy Renner was available to take on the lead role.
The Oscar-nominated star, 41, plays new secret agent Aaron Cross in the fourth movie in the franchise, taking over from Matt Damon's Jason Bourne.
Tony told the Vulture blog: "My memory of it is that we did two big waves of screen tests. (Jeremy) wasn't on the first bunch of lists that we had, and he hadn't been available because the Avengers schedule was so up in the air and they were so sketchy about putting that together... and then all of a sudden, he was on an "available" list.
"Literally, on a Monday morning, it was like "red alert". He hit the trifecta for us of what we needed to play the role, so we sent him a script right away and then went to Germany to talk to him."
Tony, who has also directed Michael Clayton and Duplicity, said casting the movie was a "nerve-wracking odyssey".
"There were people I met along the way that were completely surprising and not what I expected at all and people I completely connected with... and there were people that really fell off my truck, in a way, where you sort of go, 'Wow. There's really nothing there'," he confessed.