NEW YORK -- On a blazingly sunny afternoon, several understudies take their places on a nearly dark Broadway stage where the latest revival of "Oklahoma!" is playing.

Production supervisor Mitchell Lemsky cues a lone pianist to play the opening bars of "Oh, What a Beautiful Mornin'," and a bearded, blue-eyed actor named Stephen Buntrock strides into view.

There are no microphones to amplify his voice, which carries a surprisingly short distance in the hangar-like Gershwin Theater. He wears street clothes, as do all the other actors, and no makeup. Offstage, the actress understudying Ado Annie windmills her arms and touches her toes, preparing for one of the show's demanding dance numbers.

As with any rehearsal, it's like watching the ghost of the full production. Only today, that feeling is especially strong. This group will never perform together in these roles in front of a paying audience.

Instead, they will appear almost nightly in the ensemble, playing minor parts and adding their voices and dance steps to the musical numbers. At a few performances -- if a principal actor calls in sick or goes on vacation -- one of them might take over a lead role.

As Broadway jobs go, understudying is among the most thankless.

Understudies are often maligned in novels and movies, depicted as ambitious climbers who will do anything for a moment in the spotlight.

Nor are they viewed favorably by audiences. Many theatergoers dread finding small white papers tucked into their Playbills that begin, "At tonight's performance, the role of the Phantom -- or Max Bialystock -- or Jean Valjean -- or Mrs. Robinson -- will be played by ..."

Buntrock, who is understudying the lead role of Curly, and other actors certainly understand the disappointment. "Your first thought is that you're not seeing the show you're paying 90 bucks to go see," the actor says, shrugging.

However, he says, the opposite is true.

"In fact, you are seeing the exact show. That's the key to being an understudy: Making the role into your own character but forming it to make sure you are not going to be changing the show."

"I think probably the most common misperception is that the understudy isn't as rehearsed or as capable as the leading actor," says Amy Bodnar, who covers for the role of Laurey in "Oklahoma!"

Lack of preparation is normally only a concern if an understudy is tapped early in a show's run. Understudies begin rehearsals for lead roles late -- usually after previews start -- at which point the principals have already been rehearsing for four to six weeks.

"With understudies, you're forced to work more quickly, especially at the beginning, to get the show covered. You do more detail work later," says Lemsky, who oversees all rehearsals for "Oklahoma!"

There are understudies for understudies, too. They typically begin rehearsals after the director feels the first group of covers is prepared to take the stage.

At this point, Lemsky believes Buntrock, Bodnar and the other understudies are well prepared to go on. "The next step is to see how what they're doing works with an audience present," he says. "And the only way to tell that is to wait for them to actually go on."

Understudy rehearsals will continue, about one a week, for the duration of the show's run. Still, for Buntrock, Lemsky's confidence is both frightening and affirming. "It's a compliment, but it's also quite scary," the actor says. "It just takes you one step closer to the realization that you will be going on sometime."

"Sometime" could be days, weeks or months from now -- even never.

Patrick Wilson, the principal actor who plays Curly, has a reputation for perfect attendance.

"Patrick is a tank," Buntrock says. "I was talking to Matt Stocke, a good friend of mine, who understudied him over at 'The Full Monty,"' Buntrock says, referring to the Broadway hit in which Wilson originated the leading role of Jerry Lukowski. "The only time he missed was for his vacation."

But Buntrock is no Eve Harrington (the conniving understudy who betrays just about everyone in "All About Eve"), quietly plotting Wilson's demise between shows.

"If I was back here being a little back-stabber, going, 'Oh, I could do that so much better,' that would serve no purpose whatsoever," he says. "I know Patrick is an amazing talent, so I'm honored to be his understudy."

Understudies everywhere must have taken heart last month when the little known Brad Oscar stepped into the role of Max Bialystock in "The Producers." Oscar had understudied the original Bialystock, Nathan Lane, before Lane left the production.

Sutton Foster, star of "Thoroughly Modern Millie," lived a similar fairy tale last year. Erin Dilly had originally been given her role, but developed vocal problems during the show's pre-New York tryout. Foster, Dilly's understudy, won the lead.

One of the biggest challenges of understudying, Buntrock says, is adhering to a principal's performance closely enough that a show's other actors aren't thrown off.

During the run of the musical "Jane Eyre," he went on for the lead, James Barbour, three times. The first two times he played it safe, closely emulating Barbour's performance. "The third time, I thought I could act it, my own inflections, and it just fell apart. I started forgetting lines. And that was the last time I went on, so I never redeemed myself," he says with a laugh.

According to Bodnar, "You have to respect what's going on out there at night. But Mitchell has also given me a lot of free rein to be myself. And that's a gift."

Buntrock, 33, got his big break in 1999, when he was cast as the lead in the national tour of "Martin Guerre," by the authors of "Les Miserables." The musical was headed for Broadway, and stardom for Buntrock seemed imminent, but a New York production never happened. The show's producer, Cameron Mackintosh, blamed lack of theater space in New York.

The first offer Buntrock got after "Martin Guerre" folded was as a supporting player and understudy to the lead in "Jane Eyre," which had a brief run on Broadway last year.

"At first, I was like, 'understudy?'" says Buntrock, who thought it was the producers' way of saying he was "not quite the right talent for the part, but just good enough to get in there."

In the end, he took the job. His change of heart, he confesses, stemmed partly from financial considerations -- he has a 7-year-old daughter in Chicago to support. "Being on Broadway is a good paycheck," he says.

He had also adopted a more laissez-faire attitude toward his career following "Martin Guerre." It's the same reason he took his current job in "Oklahoma!"

"I don't need to be a star. I would rather just be respected for being a hard worker and be trusted to do a good job," he says. "You always have to think that there are thousands of other young men who would want to have this job in a second."

And who knows? There's always the possibility that Buntrock will end up singing about beautiful mornings full-time.

After all, scores of performers have achieved fame after paying their dues as understudies, among them: Walter Matthau, Joanne Woodward, Kevin Spacey and Patricia Neal.

Shirley MacLaine, Broadway's most famous understudy success story, rose to stardom after taking over for an ailing Carol Haney in the 1954 hit "The Pajama Game." A movie producer saw MacLaine while she was playing the role, signed her to a contract, and the following year she found herself starring in Alfred Hitchcock's "The Trouble With Harry."

"If the role came my way, of course I would take it and grab a hold of it, just like Brad Oscar," Buntrock says. "That's the million dollar dream."