Antoine Fuqua says it will "always break [his] heart" passing up the chance to helm 'American Gangster'.
The 57-year-old filmmaker was all set to direct the 2007 biographical crime film, but departed due to "creative differences" with Universal.
Sir Ridley Scott, 84, ended up taking charge of the flick, which starred the likes of Denzel Washington and Russell Crowe, and Fuqua will always regret his decision to quit but admits, in hindsight, he wasn't ready for the job.
He said: "It breaks my heart just to say it out loud.
"I didn't know enough then.
"I don't think I navigated it the way I should have or had a full perspective and understanding of the business, like the fiscal responsibilities and the pressure that everyone's under, including the executives.
"You do have to pause and take in the big picture.
"That one got away from me, and that will always break my heart."
Fuqua is gutted he missed out on another opportunity to work with Washington again, who he has worked with on several blockbusters since 2001's 'Training Day'.
In the same interview, the 'Guilty' director shared how he instantly clicked with the 67-year-old gangster film legend.
He recalled how he empowered him as a "nervous" newcomer to the directing world on the set of 'Training Day'.
Fuqua told The Hollywood Reporter: "On [Denzel's] very first scene, I remember covering Denzel and I got everything I wanted as a director.
"I felt good about it.
"But I'm this young guy and I'm a little nervous. I don't want to screw this up.
"So I turned to Denzel and said, 'You want to come to the monitor and take a look to see if you're happy?'
And Denzel turned to me and said, 'Man, you're flying this plane. Call me when you're ready,' and then got up and walked away.
Then I looked at Ethan [Hawke, who played Jake Hoyt] and he gave me a look like, 'Yep,' and he walked away.
"It was a confirmation that they trusted me. It empowered me to really go for it."