Captain America: Civil War is on the horizon and star Sebastian Stan says the film is likely going to hit fans pretty hard.

"I think it's going to be an epic experience for people," Stan told ET's Ashley Crossan during a press junket for his upcoming dramedy The Bronze. "I'm very excited for people to hear and see what side everybody ends up on, 'cause it gets a little heartbreaking."

In the highly anticipated Marvel action extravaganza Stan plays Bucky Barnes, a.k.a. the Winter Soldier, a hero-turned-mercenary-turned-hero-again who teams up with his friend, Steve "Captain America" Rogers, in war against Iron Man over government regulation that splits the country's heroes into two opposing ideological factions.

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Being on the front lines of the titular civil war, Stan shares an much talked-about fight scene with Robert Downey Jr., which Stan said was "amazing."

"It's inevitable not to geek out a little bit around Robert Downey Jr.," the 33-year-old actor gushed. "Just to be around him [and] fight across from him was definitely a highlight!"

Stan also showered praise on fellow Marvel star Paul Rudd, who reprises his role as Ant-Man in the upcoming Captain America installment.

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"I couldn't keep a straight face with Paul Rudd!" Stan shared. "I’m a huge fan of his, but also he's just so funny and witty and he was always like cracking me up."

While Captain America: Civil Wardoesn't hit theaters until May 6, Stan's upcoming project, The Bronze, co-starring Melissa Rauch, Thomas Middleditch, Cecily Strong and Gary Cole, comes out March 18.

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