Josh Brolin has played complex villains in two separate Marvel films in 2018, "Avengers: Infinity War" and "Deadpool 2." But it wasn't until he saw future co-star Benedict Cumberbatch's performance as Smaug in "The Hobbit: The Desolation of Smaug," that he was convinced to take on the villainous role in "Avengers."

During an interview with SiriusXM, Brolin discussed what made him want to join Marvel's record-breaking "Avengers" movie. The actor explained that when he was deciding whether or not he wanted to play Thanos, he turned to YouTube to do some research.

There, he discovered a behind-the-scenes video of Cumberbatch (who plays Doctor Strange in the MCU) working with motion capture technology to portray the menacing dragon in the 2013 "Hobbit" film.

After seeing the dedication and bar set by Cumberbatch, Brolin agreed to join "Avengers: Infinity War."

"He's [Cumberbatch] crawling around like a snake and he's snapping his tongue out, doing this incredible performance and I saw that and was like, alright, that's the bar," the actor said. "This is not b-------. This is something you have to sink your teeth into — conviction, embarrassment, all that kind of stuff."

The actor added that there was "pressure" going into "Avengers: Infinity War" and "Deadpool 2" as villains (he played Cable in the latter), but the reception from fans validated his experiences.

"The critics were always talking about Marvel villains being the weak point, so you have that pressure," Brolin said. "The way that people are reacting to this character as if he truly exists is kind of phenomenal."

Brolin went on to say: "I'd never done anything like that — motion capture. I thought I was going to be behind a bunch of lights and a bunch of cameras, but it wasn't like that. It was practical, working with people. It's a phenomenal process."

This is what Brolin and co-star Robert Downey Jr. looked like while filming "Avengers: Infinity War." Marvel

This isn't the first time Brolin has talked about factors that convinced him in movies. In an interview with Jimmy Fallon in May, he said that he almost turned down the opportunity to be part of "Deadpool 2," but his wife persuaded him to read the script and consider it.

Watch the video below.

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