The third season of Fargo centers around brothers Emmit and Ray Stussy. The pair couldn't be more different, and yet they're both portrayed by star Ewan McGregor.

"The challenging part is making sure they're both unique people," McGregor told The Hollywood Reporter at the premiere for Fargo's new season, which kicked off FX Networks’ upfront on Thursday in New York City. "The challenge is making sure they're both different and believable people and the truth is that they feel very different when I'm playing them, so that's good and helpful."

Indeed, though the Stussy brothers share the same last name, the two characters were certainly not cut from the same cloth. When viewers meet Emmit in the premiere, he is the happily married, well groomed and well off parking lot king of Minnesota. Ray is introduced in his slightly older brother's shadow, a balding and pot-bellied parole officer with one of his parolees on his arm (Mary Elizabeth Winstead). A petty theft from when the brothers were young — something that sparks the events that kick off the season in the premiere — grew into an adult sibling rivalry, which forked separate paths for the pair.

Despite the obvious challenge of playing a dual role, McGregor (who played clones in The Island and Jesus and the devil in Last Days of the Desert) admits that he was somewhat blasé about the challenge — at first.

"I felt like I understood them from the writing and I don't make the job very complicated for myself as an actor," said McGregor, who also had to learn how to master the distinct Fargo accent. "But when I got up there [to set], I suddenly went, 'F—, I've got two jobs to do here.'"

After discussing at great length how the two characters should look with creator Noah Hawley, McGregor said he got a lot of help from his friends in the costume and makeup departments to achieve Ray's appearance. One of the longer scenes in the premiere sees McGregor as Ray in a towel, displaying the results of that work.

"I got a lot of help in terms of what they look like," he says, "but in terms of what they are, and how they sound and move, that was down to my instincts."

The Trainspotting star added, "I get dressed and I'm ready as Ray, and I start to feel like Ray. And the same as Emmit. And I just trust that."

That instinct is likely just what Hawley was looking for when he thought up the idea of having one person play his two leads.

"We wanted an actor of a certain caliber," he told THR ahead of the screening at the SVA Theater. "You need to make it a compelling job for them. But I really thought, if they're family, you want to see the family resemblance. You want to feel that they're brothers. Obviously they look very different, but there's still that inherent Ewan-ness in both."

The season, set in 2010, will ultimately wind down the twisted path these brothers embark on. One that, in very Fargo fashion, will quickly lead to murder, mobsters and even cut-throat, competitive games of bridge.

"This year, I saw someone said it's the most Fargo version of Fargo yet," said Hawley, referencing the original film from the Coen brothers. "It captures the intimacy of the movie and our first season and then builds to a scale that's similar to our second season. I think it's nice to go back to something that feels smaller and then build it. I think it's get better and better — the potential for what the show can be just keeps growing."

And McGregor agrees: "It's maybe a slightly more intimate season. The story is very personal and full of heart. But it's as full of quality as the other two were. It's really good writing."

The season also stars Carrie Coon (The Leftovers) as local police chief Gloria Burgle, Winstead as Ray's crafty girlfriend Nikki Swango and David Thewlis as a mysterious villain, V.M. Vargas. Though, neither women were present at Thursday's premiere and upfront event because they were "beginning their day shooting this epic sequence that I can't tell you about that happens in an episode that I can't specify" in the freezing location of Calgary, teased Hawley while introducing the episode.

"It's quite cold," McGregor recalled to reporters, crediting Merino wool long underwear and the experienced crew for keeping him warm through days that reached a low of 29 degrees below zero. "[But] we're not walking around in T-shirts, which sometimes is the case when you find yourself shooting a film and it's freezing but you're not meant to be. All our characters are dressed for the cold usually, anyway. I think in season one, there was a guy who had to be naked and run across an ice field, but luckily that wasn't me!"

After the premiere, McGregor joined a host of FX stars at the upfront party at Lucky Strike Manhattan. Filling up the bowling lanes were the casts and teams from The Americans, You’re the Worst, Archer, Legion and upcoming drama Snowfall. American Crime Story: Versace's Darren Criss and Edgar Ramirez, American Crime Story: Katrina's Cuba Gooding Jr., Feud: Bette and Joan's Alfred Molina and Sarah Paulson, who appears in Feud and will star in Katrina and the upcoming season of American Horror Story, were also in attendance.

Fargo returns April 19 on FX.