Global music superstar Justin Timberlake has just received some of the best reviews of his career and it's not for his latest album. Instead, he's drawing kudos for his performance in Nick Cassevetes' new dramatic thriller "Alpha Dog," which premiered last week at the Sundance Film Festival.

"Dog" is based on a real-life incident involving Jesse James Hollywood -- one of the youngest and most powerful drug dealers in Southern California's history. Hollywood wasn't some stereotypical South Central thug. He was a white kid living in the L.A. suburbs who lost control and ended up kidnapping the brother of one of his enemies, resulting in tragedy. For legal reasons, Hollywood has been renamed Truelove (played by a spirited Emile Hirsch) and Timberlake plays his trusted "business partner" Frankie Nutz. In researching the part, Timberlake visited the real Nutz -- Jesse Rugge -- who is serving a life sentence in a Northern California jail.

"I did go up and spend about two to three hours speaking with Rugge," Timberlake says as we chat in a makeshift Park City, Utah, lounge. "I had a very interesting conversation with him, half of which I believe, half of which I don't."

Why? Well, as Timberlake notes, the character based on Rugge was nicknamed Frankie Nutz "because he was insane."

Audiences will be surprised (and possibly pleased) to find that Timberlake immersed himself in the difficult role by covering his body with tons of tattoos. The designs were picked by the Grammy winner and his make-up artist, and had to be reapplied every 36 hours. Besides the noticeable letters "nutz" across Timberlake's right knuckles, he says "I also had 'est. 1976' across my chest which would make the character about my age at the time -- 24."

Acting isn't a casual second career for Timberlake. He has shot three movies over the past two years including "Dog," the thriller "Edison" and "Black Snake Moan," the second feature by "Hustle & Flow" director Craig Brewer. So, does Timberlake have a meticulous plan to master the movie business and step out of the music world?

"I think the dream is to not have to really worry about it too much," he says. "In a perfect, dream world I just do the [movies] that I respond to and keep it moving. Y'know, I like both and I don't see myself wanting to give up one for the other."

No matter what effect "Alpha Dog" has on Timberlake's movie career, it's already had a big influence on his music.

"It's changed the songwriting," Timberlake says of the 14 songs he's finished for his new, untitled album. "The songwriting is so much more character driven."

Timberlake wouldn't divulge much about his top-secret follow-up to 2002's smash "Justified," but he did confirm he'd have a single out by the summer, "no doubt."

With so much time spent acting, should fans expect a different approach to Timberlake's upcoming music videos?

"In all honesty, I've sort of semi-directed my own videos," he says. "I think I will definitely take a bit more of a hands-on approach. But, these songs are so specific to a certain visual, that when I write a song I can see the video in my head. I can see the packaging, the single, the video and that's how I know I'm on the right track."

If "Dog" is any indication, Timberlake's talent will take him just as far on the big screen.

"Alpha Dog" opens nationwide this spring.