Adam McKay Details the ‘Winning Time' Casting Drama That Ended Will Ferrell Friendship

While the real-life events that inspired HBO's new series "Winning Time" is fascinating, it's the story behind the story that we're really interested in.

Ahead of the highly-anticipated drama's March release, Adam McKay is spilling all the details on how it led to his rift with longtime collaborator and close friend Will Ferrell.

Their production company Gary Sanchez Productions is to thank for some of the most iconic movies of the 'aughts -- think: "Talladega Nights," "Step Brothers" and "Anchorman" -- arguably influencing filmmakers of the next generation. However, McKay started to follow a different path in more recent years, directing political dramas like "Vice," "The Big Short" and, most recently, "Don't Look Up."

This was all well and good until McKay began to work on "Winning Time," which is about Ferrell's favorite basketball team, the L.A. Lakers. Though there were reports that Ferrell wanted to play majority owner Jerry Buss, McKay told The Hollywood Reporter in a new interview that "Will was good" with Michael Shannon taking on the role.

But then, things went south when Shannon realized he didn't jive with the direction McKay was taking the project. "It really bugged Michael that we were breaking the fourth wall," McKay explained. "He kept saying, 'I don't like this. It throws me. I'm having a hard time.'"

So, according to The Hollywood Reporter, Shannon decided to drop out of the series a week before they began filming.

Around this time, Ferrell and McKay announced they were shuttering Gary Sanchez Productions, releasing a statement that they "will always work together creatively and always be friends. And we recognize we are lucky as hell to end this venture as such."

Then, instead of handing the part of Buss over to Ferrell, McKay turned to "Step Brothers" actor John C. Reilly with an offer to join the cast, explaining, "I told him, 'We're in a weird spot here, but I'm directing the pilot and I think you'd destroy this.'"

For Reilly, this was the perfect opportunity. "I'd been sitting at my kitchen table, thinking, 'Man, I'm dead in the water, all this work, 80 movies, and I got nothing going on,' when I got the text from Adam," he told THR. But he felt obligated to give Ferrell a heads-up that he was taking the role, so he gave him a call.

Looking back, McKay admitted that he "f--ked up" by not reaching out to Ferrell beforehand. "It was at this weird moment where Will and I weren't exactly hugging each other, even though there was nothing that terrible and he called Will and said, 'Hey, McKay just came to me with this,'" McKay recalled. "And Will was very hurt that I wasn't the one to call him, and I should have."

E! News reached out to Ferrell's rep for comment and didn't hear back.

Reilly, meanwhile, is remaining neutral, explaining to THR, "Will is one of my best friends, Adam is one of my best friends, I was delighted to get the job and that's all I really have to say."

In October, Ferrell addressed his and McKay's decision to go their separate ways, chalking it up to creative differences. "Adam was like, 'I want to do this, and this, and this'; he wanted growth and a sphere of influence, and I was just like, 'I don't know, that sounds like a lot that I have to keep track of,'" he told The Hollywood Reporter. "To me, the potential of seeing a billboard, and being like: 'Oh, we're producing that?' I don't know. ... At the end of the day, we just have different amounts of bandwidth."

Two months later, McKay acknowledged he mishandled the situation, but admitted that Ferrell "took it as a way deeper hurt than I ever imagined."

"Maybe there was a little shadow in there where I wasn't able to confront a harsher, darker side of myself," he explained to Vanity Fair, "that would ultimately err on the side of making the right casting choice over a lifelong friendship." Fans can see if the sacrifice was worth it when "Winning Time: The Rise of the Lakers Dynasty" premieres on HBO Sunday, March 6.