If you haven't checked your side and rearview mirrors recently, look now because Peter Sarsgaard is approaching. The 33-year-old actor, who plays a bisexual research assistant in Kinsey, the new Liam Neeson-fronted biopic about sex researcher Alfred Kinsey, has been nailing quality supporting roles for almost a decade, perpetually on the brink of becoming a ubiquitous name. Sarsgaard has played both murderer and murderee: His film debut was as one of Sean Penn's victims in Dead Man Walking, and four years later Hilary Swank was Sarsgaard's victim in Boys Don't Cry. Most recently he's been attracting attention for supporting roles in Zach Braff's ode to Jersey, Garden State and the bad-ethics biopic Shattered Glass.

Despite the stream of success, however, Sarsgaard still has to fight for the big-time roles. He says there are at most 10 available each year, and he's got a shot at fewer than half of them. "Jude Law is going to play six of them, so there's another four left," he calculates, with a trace smile. "Ed Norton will play another one. There's a lot of competition for [the] best roles." Sarsgaard had to push Kinsey's writer/director Bill Condon (who also did Gods and Monsters) to land the role of Clyde Martin, Kinsey's collaborator, surrogate son and constant companion.

In real life, Martin seduced both Alfred Kinsey and Kinsey's wife, Clara, who is played by Laura Linney in the film. Though Sarsgaard seemed comfortable talking about his sex scene with Neeson, he admits he was uncomfortable during filming. "I think scenes like that are naturally uncomfortable," the actor says. "There are so many things I do as an actor that are like that -- like raping Hilary Swank [in Boys Don't Cry]. You worry about how she's feeling the whole time, if she's going to be alright with it. Kissing Liam, I'm worried about how he's going to feel... The only thing you worry about with yourself in a situation like that, the only reason you have to be afraid, is that you might be turned on... As you can tell from the movie, he nearly takes my head off, so there was no danger of that."

This is not the first time Sarsgaard has worked with Neeson. The actors first collaborated in the submarine thriller, K-19: The Widowmaker -- now, in Kinsey they play hide-the-torpedo. Will this deviant behavior fly in red state multiplexes? "I actually think it'll play quite well where I'm from, which is St. Louis," Sarsgaard says. "I think a lot of the humor in the movie depends on you being a little bit squeamish or titillated by sex. The tighter you are going in, the more you'll laugh. If you're, you know, somebody's who's into swinging and free love, I doubt you'd find a lot of it funny."

Speaking of love, Sarsgaard has been dating actress Maggie Gyllenhaal for three years. All the while, he's steadily attracted a following of high-minded females. "Those eyes are so interesting," cooed Laura Linney recently at a press junket. The eyes in question (they're green), along with Sarsgaard's unaffected, soft-spoken articulateness contribute to a weary, wise look that can be alternately smug, mysterious and handsome.

Though he eventually may start snatching roles away from Jude Law, right now he's all booked up. Next year he'll be airborne with Jodie Foster in the thriller Flightplan and he recently finished the "conceptual horror movie" Skeleton Key with Kate Hudson. Hating Her, with Sarah Jessica Parker and Diane Keaton, and Craig Lucas's dramatic indie The Dying Gaul should also be out sometime next year. Considering his track record, expect Sarsgaard to signal and move back into the right lane before making another calculated pass on the path to fame.