In high school in suburban Seattle, Erika Rolfsrud remembers, "I was told I'd never play Juliet. It was playing somebody's mother or the loose woman." Eventually 5-foot-8 with a dusky voice, she was well into college before she played a lead.

Since then, they've been frequent and mainly classical, often in Seattle, more often in Southern California, where she acted at San Diego's Old Globe Theatre, and eventually in New York.

She made her Broadway debut under Old Globe director Jack O'Brien in Tom Stoppard's epic "The Coast of Utopia" trilogy, then was understudy last year to Cynthia Nixon in Nixon's Tony-winning role as the grief-challenged Becca in David Lindsay-Abaire's "Rabbit Hole."

You could say that she's now caught up with her acting age and even passed it, because she doesn't look her 40 years. "Yes, put that age in for casting directors to see," she says, claiming she has been considered too young for roles that are really her age.

Whatever age, the lively reddish-blonde with striking blue eyes (the color "depends on the day," she says) sitting outside a Downtown Pittsburgh coffee bar -- Starbucks, of course, for this Seattle native -- is clearly a lead. And now she's at the Pittsburgh Public Theater, in "Rabbit Hole," playing that same Becca.

She put off auditioning for post-Broadway productions for some time. As she said on her Web site (www.erikarolfsrud.com -- a site attractive and forthright, like her), "I just felt too close to it. ... I didn't want to do a production thinking the whole time, 'Well, they didn't do it like that in New York!' And selfishly, I want my performance to be my own without the shadow of an amazing performance looming in my mind."

Part of the attraction here was director Rob Ruggiero, a Public regular. And she's glad she waited. As an understudy, your job is to step in and reproduce someone else's performance, so "you learn the role outside in." But playing the role for yourself, you develop it "inside out."

In rehearsal here she has had many "ah ha!" moments, discovering how something felt or what it meant. But that four-month experience of working on the role on Broadway is still part of her, and "everything you are goes into it. So I can't say Cynthia didn't influence this performance."

Rolfsrud is Norwegian ("I love performing in the Midwest because they can pronounce it like [finger snap]! In Minnesota, I never had to spell it.") and grew up near Seattle, where she went to Sammamish High School -- and she spells it, using her old cheerleader cheer, ending, "Let's go!"

She knew then she was headed for acting. She remembers when her grandfather showed her "Singin' in the Rain" and she fell in love with Gene Kelly, so she wrote him and he replied with a signed picture. "I nearly wet my pants."

She went to Whitman College in central Washington, but it was during a summer program at Oxford, England, that the career die was cast. She was anxious. "It was my first real time away from home, and I thought, 'God, if I'm not supposed to be following this, please let me know.'"

It went well. She left her college graduation at full speed, hopping a plane for the Utah Shakespearean Festival. After several years of mainly classical theater, her observation of other actors gave her a good line on which schools to prefer, and she opted for the Old Globe's intensive two-year MFA.

"I didn't realize the prestige of the Globe." It gave her connections with O'Brien, who eventually cast her in his two-part "Henry IV" that starred John Goodman in San Diego and then went on -- without her or any other of the San Diego actors except Richard Easton and adaptor Dakin Matthews -- to Lincoln Center.

So Easton and Matthews were her teachers, too. She's hoping her schedule allows her to see Matthews' King Lear at PICT.

For the Broadway "Rabbit Hole," Seattle director Dan Sullivan asked her to understudy "out of the blue. ... Understudying is the most underrated job there is, because of the stress," but she found it a "blessed experience, with a perfect cast and lovely people backstage."

As to the star, "Cynthia Nixon for me is the bar as to how to treat people. There is no diva there at all."

Rolfsrud never did perform in the role, but there was one two-performance day when she almost did. Nixon was very sick, so for the matinee, Rolfsrud was in costume, hair and makeup, ready to jump in at any point during the show if Nixon couldn't continue.

"It was terrifying, but I became preternaturally calm." She trailed Nixon's dresser around backstage the whole show, rooting Nixon through her ordeal: "Come on, girl, hang in there!" That may be contrary to expectation, but, "as I get older, I no longer have fantasies of being the heroine of the show. And that wasn't the way I wanted to go on in the role."

Gradually Nixon's medicine took hold and she was better for the evening show. "She made it through. I've understudied other stars in other productions," -- Rolfsrud offers no names -- "and I've thought ...," and here she makes an undecipherable noise indicating consternation and says, "I can't wait to see how you spell that." But as to Nixon, "she really deserved that Tony."

Now the role is hers. Naturally ebullient, she brought books and other distractions with her, because "playing a role that's sad, you can dry up." But she doesn't seem one whose supplies of energy and optimism are in any danger.