Nearly three months before the 2014 release of Captain America: The Winter Soldier, the film’s directors, Joe and Anthony Russo, had already signed on to helm the third installment in Marvel’s Steve Rogers saga, the film that would become Captain America: Civil War.

It might have been a risky move for some, but for the Russos, who have since committed to wrapping up Marvel’s Phase Three by directing the two-part Avengers: Infinity War, the decision was a “no brainer.”

“The experience of making Winter Soldier was fantastic!” Anthony told ET. “We loved what we did creatively, and we didn't feel like the story was finished that we were telling in that film… We wanted to keep going with it.”

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ET’s Nischelle Turner was invited on the set of Civil War to chat with the directors about the film, which sees Captain America (Chris Evans) butting heads with fellow Avenger Tony Stark (Robert Downey Jr.), a.k.a. Iron Man, and they revealed that part of the challenge in directing the newest installment was finding the chinks in the armor of the “Star-Spangled Man With a Plan.”

“Part of Captain America's superpower is that he's such a strong, ethical, moral-centered, moral character. He's pretty hard to break on that level,” Anthony explained. “It's hard to deal with a character like that because we like vulnerabilities in our characters and in our storytelling. You have to work really hard on Captain America to find those vulnerabilities.”

“That's one thing we're most excited about in this movie,” he continued. “I think we finally push him in a place that's going to surprise people, and a place that he's never been before -- but it's a very human place.”

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Like Winter Soldier, Civil War centers around Captain America and his relationship with old friend and fellow soldier Bucky Barnes (Sebastian Stan), whom the HYDRA baddies have transformed into the merciless Winter Soldier. But most of the Avengers crew also return to take surprising sides in the Cap vs. Iron Man showdown, including the Black Widow (Scarlett Johansson), Falcon (Anthony Mackie), Hawkeye (Jeremy Renner), Scarlet Witch (Elizabeth Olsen), Vision (Paul Bettany), and Rhodey/War Machine (Don Cheadle). Paul Rudd’s Ant-Man character, Scott Lang, also joins the fray as a member of Team Cap.

The film even features some new heroic faces -- a quickie origin story for Prince T’Challa of Wakanda (Chadwick Boseman) has us super excited for Ryan Coogler’s standalone Black Panther film, and there’s a surprisingly in-depth intro to Marvel’s new Peter Parker/Spider-Man Tom Holland -- but it’s not exactly Avengers 2.5.

“It's Captain America’s point of view in the film. The main story is it's incredibly personal to him as a character. The movie starts with him. It ends with him,” Joe explained of Civil War. “Some people think it gets overly complicated when you're bringing other characters. But those characters are there to serve us the main storyline. The main storyline is Captain America.”

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For the directors, part of the appeal in telling a true Captain America story is the accessibility of the character, who fights bad guys with only his enhanced strength and vibranium shield.

“He doesn't fly across the sky like Iron Man, he doesn't turn into a green giant like Hulk, he doesn't come from another world like Thor,” Anthony related. “He's basically a man, only a little more so. We feel like he has a human-sized scale to him, both in his powers and his sort of relatability.”

Captain America: Civil War hits theaters May 6.

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