Although her auburn tresses may suggest otherwise, Debra Messing is not Irish. "I'm a Polish-Russian Jew," she admitted. "I have been mistaken for Irish before because of my hair, but I've definitely never been mistaken for a farmer."

So what's a nice Jewish girl doing schlepping turf on a cattle farm in John Patrick Shanley's Outside Mullingar, a new romantic comedy set in rural Ireland? "Thanking my lucky stars," said Messing, who worked with a dialect coach to perfect her County Westmeath brogue.

Best known to television audiences for her roles on "Will & Grace" and "Smash," Messing makes her Broadway debut in the world-premiere Manhattan Theatre Club production, which opens Jan. 23 for a limited engagement at the Samuel J. Friedman Theatre. Inspired by the Bronx-born playwright's Irish roots, the play follows the rocky relationship of eccentric neighboring farmers Rosemary and Anthony over the course of four years. Messing stars as Rosemary opposite Tony winner Brían F. O'Byrne, who is indubitably Irish. "I definitely felt the pressure when I realized, 'Wait, he's from Ireland! He doesn't have to learn an accent?' It's intimidating, sure, but absolutely thrilling," she said. "I'm a longtime fan of Brían. He's so funny, so open, so brilliant."

Outside Mullingar reunites O'Byrne with Shanley and director Doug Hughes, the Tony-winning duo behind MTC's Doubt. It's also Shanley's tenth play at MTC, where Messing landed her first New York theatre job in 1993 — understudying Mary-Louise Parker and Polly Draper in Shanley's Four Dogs and a Bone — after receiving her degree from NYU's Tisch School of the Arts. Messing is excited "coming back full circle to John Patrick Shanley and MTC, the beginning of my journey as an actor."

Remembering her work 20 years later, Shanley personally requested Messing for Outside Mullingar. "He's always had a very special place in my heart," she said. "I went on quite a bit in Four Dogs and a Bone, and we'd go out for drinks afterward when he'd pop in to watch the show. I remember sitting with him at a bar and him telling me, 'You're gone.' I said, 'What do you mean?' 'Los Angeles is going to find you and we'll never see you again.'"

Shanley was correct, of course, but Messing didn't disappear without a fight. She next appeared in Paul Rudnick's The Naked Truth at the WPA Theatre. In 1997, after starring in the short-lived Fox sitcom "Ned & Stacey," she even turned down a high-profile NBC pilot in favor of returning to MTC for Donald Margulies' Collected Stories. "I kept imagining how I'd feel if I turned down Collected Stories and watched as another actress was cast, knowing I'd never have that experience. I realized that if I was meant to be on television, there would be another great opportunity."

Indeed the following year Messing nabbed the role of lovable neurotic Grace Adler, every gay man's dream bestie, on NBC's "Will & Grace," which ran eight seasons and earned her an Emmy. Though she said she got her theatre fix filming in front of a "particularly passionate" live audience, Collected Stories was her last stage appearance until now.

"There have been some close calls, but it usually ends up falling apart because of scheduling," continued the actress, whose films include "Along Came Polly," "The Wedding Date" and "The Women." "I knew that one day I'd get back to my first love."

Call it more luck of the Irish that Messing recently spent two seasons as lyricist-librettist Julia Houston on "Smash," NBC's now-canceled series about the backstage Broadway drama. "The rigors of the theatre were part of my trepidation to do Broadway," she explained. "Broadway actors have to be athletes, and I didn't know if I was built for it anymore. But working on 'Smash,' living in that world, reminded me of my passion for theatre."

Did "Smash" inspire her enough to do a musical? "No," she declared with a cackle. "Trust me, people have tried for years to make it happen, but that would send me to a sanitarium. Just having to keep your voice consistent every day? I'd be a freak of nature with 17 scarves around my throat and humidifiers... It would be horrible for me and everyone else in my life."