Tony Gilroy reveals that they were looking for specific things when they were casting the role of Aaron Cross in The Bourne Legacy.
The Bourne Legacy is the fourth film in the franchise but the first without Matt Damon in the lead role.
Instead the role of Cross is introduced and will see Jeremy Renner take on the part for the first time.
Speaking to Flicks and Bits the director said: "We had the opportunity with Aaron Cross, somebody who's just as soulful and just as complicated, so we really needed an amazing actor - and Jeremy Renner is that.
"We also needed someone who is physically extraordinary, because we knew what we wanted to do and we knew what was expected."
"Then we also needed, as the third piece, which was perhaps the most difficult, we needed someone who has those two skills, those two attributes, but wasn't so clearly identified in the audience's mind - that they didn't have a perfectly clear picture about them as another character, or an idea about them.
"We wanted to identify him as our guy, who was just enough out of focus to bring him forward. That was the trifecta that we were looking for."
Renner will star alongside Edward Norton as well as Oscar winner Rachel Weisz.
The Bourne Legacy is released 13th August.