Cobie Smulders brings her A-game opposite Tom Cruise in 'Jack Reacher'

Cobie Smulders didn't have wild action dreams about her starring role alongside Tom Cruise in Jack Reacher: Never Go Back. And certainly none that involved beating him in a footrace.

The star of the TV's long-running comedy How I Met Your Mother thought she'd be overshadowed onscreen by one of the world's biggest stars.

"I thought, 'This is going to be a Tom Cruise movie' — I was going to be along for the ride, maybe I'd be able to kick somebody," says Smulders, 34.

She got an action awakening after landing the part of Major Susan Turner in Never Go Back (in theaters Friday).

In the follow-up to 2012's Jack Reacher, Smulders' Turner holds the same job and rank that Cruise's former military police investigator once held. She fights alongside him, drives with Cruise in the passenger seat and even sprints faster.

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Cruise and director Edward Zwick insisted on these noticeable details to make Turner a Reacher equal — an important premise of Lee Child's 2013 novel Never Go Back, upon which the book is based, says Zwick. "Tom wanted (Smulders) to be toe-to-toe, not just running, but also in making decisions in the film. She's his peer," he says.

Smulders has appeared as munitions-savvy Maria Hill in Marvel films (The Avengers, Captain America: Winter Soldier) and TV's Agents of S.H.I.E.L.D. But the new role was a physical step up — made all the more difficult given that Smulders met Zwick to discuss the part while on crutches after fracturing her knee.

The injury's cause was decidedly unwarrior-like. "It was a stupid, random accident; I actually just tripped," says Smulders. "I have to come up with a better story about that. But I just had to say, 'Trust me, I'll work hard.' "

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Smulders insists she's flummoxed why she got the part.

"I don't know how I got so lucky to move from one genre to the next," says Smulders, who points out that before being cast as Robin Scherbatsky in How I Met Your Mother, she was an unknown Canadian actress with no comedy experience.

"For some reason, I'm fooling people into thinking I'm much stronger than I really am. I wish I could muster that strength in my personal life, like when I fall and trip in my apartment."

Smulders trained for months once she got off the crutches, incorporating repetitive boxing techniques for her screen battles. When Turner brawls onscreen, she uses anything handy, from a lethal garden hose to a meat tenderizer. "A girl's gotta do what a girl's gotta do," says Smulders.

She was ultimately glad to be just ahead of Cruise when the two spent days sprinting for the running scenes. Her selfish reasons: Cruise is really fast.

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"There were a couple of moments where he was ahead, and I'd have to say, 'Slow down, slow down' without moving my mouth too much on camera," says Smulders. "When I was in front, we ran at my pace."

Not that it was easy.

"That look of pain on my face is not acting," says Smulders. "Susan Turner is thinking, 'Let's get to a safe place,' but Cobie Smulders is thinking, 'Let's just get through this day.' "