Funnyman Patton Oswalt says he dug deep for a serious turn in director Jason Reitman's "Up In the Air" follow-up "Young Adult," spending months with an acting coach to work out the complex emotional baggage of his physically disabled character.

Raves for Oswalt's performance are already pouring in, with the stand-up comic set to be honoured Wednesday with an acting award at the Whistler Film Festival.

"Young Adult" -- which hits theatres Dec. 16 -- reunites the Montreal-born Reitman with his "Juno" screenwriter Diablo Cody, and stars Oscar-winner Charlize Theron as a morally bereft writer of young adult novels.

Oswalt, best known as Spence from "The King of Queens," plays a man whose legs were damaged by a brutal high school beating. The self-described acting "neophyte" admits to having had some qualms about the tricky role.

"Diablo wrote such a good script and such a nuanced script that there were a million ways to steer it in the wrong direction," says Oswalt, whose increasingly diverse credits include HBO Canada's "Bored to Death," The Movie Network/Movie Central's "United States of Tara" and the Adult Swim series "The Heart, She Holler."

"That's what I was most worried about -- that I would kind of fumble some of the transitions between the darkness and then the lightness, which I think are handled so brilliantly. Just when I first sat down and read the script I was like, 'Oh boy, I don't want to fumble this.' It's the combination of, 'Oh I'm so thrilled to get offered this,' and 'Oh man, I don't want to mess this up."'

Oswalt's Matt Freehauf was savagely beaten by jocks as a teen, leaving his legs permanently damaged and forcing him to walk with a brace. Matt serves as a moral compass for Theron's deluded character Mavis Gary, who returns to her hometown looking to relive her glory days and rekindle a romance with her now married ex-boyfriend, played by "A Gifted Man"'s Patrick Wilson.

Oswalt says he consulted an acting coach and a physical therapist to prepare for the role, and thought a lot about Matt's troubled backstory and how that must have shaped his upbringing.

"And not just the incident that scars him but what he went through to recover from it, which I think probably shaped his personality and worldview just as much as the damage that the attack did," Oswalt says by phone from Los Angeles.

"I just wanted less and less to have to think about so I could be more present in the scenes with Charlize. She's a really instinctual actor and I really didn't want to be sitting there with eight other thoughts on my head while she's just rolling with it."

All that work appears to be paying off.

Several early reviews have singled out Oswalt's performance as a standout, with the Whistler prize is seen by some as a precursor to a possible Oscar nomination for supporting actor.

"The whole thing just took me by surprise," Oswalt says of the multiple kudos. "It's extremely gratifying and kind of stupefying at the same time, I don't quite know what to think of it."

Oswalt, whose other big-screen ventures include "Big Fan," "The Informant!" and "Ratatouille," says he appreciated a hands-off approach from Reitman that helped him focus on building a rapport with Theron.

"What's actually kind of cool is he didn't really give Charlize and I a lot of notes on our characters. He trusts us enough to just sort of figure it out for ourselves. I think he wants that process to happen organically and he's more excited as a director to capture that on film rather than to try to manipulate it."

Oswalt notes the effusive reviews have introduced him to a world of awards-season politicking that typically ramps up with the big fall movie releases.

He says he's been doing his part to promote the film among key industry players, but insists it's far from a crusade.

"So far it doesn't feel like politicking to me because I get to go to these cool events and meet other people whose work I've always respected," says Oswalt. "I'm still such a fanboy with this stuff that it doesn't feel like I'm pressing the flesh for no reason."

Oswalt says his Whistler visit will be especially brief, leaving just enough time to attend a screening of "Young Adult" on Wednesday night and accept a festival award for supporting performance of the year immediately afterwards.

The five-day Whistler Film Festival kicks off Wednesday with other celebrity guests expected to include actor Jay Baruchel, who will receive an emerging screenwriter award as he prepares to release his hockey script "Goon" to theatres next year.

On Saturday, the festival hosts a tribute gala to "Take Shelter" and "Boardwalk Empire" actor Michael Shannon, who is currently shooting "Man of Steel" in Vancouver.