I think it's fair to say that the cast of Women on the Verge of a Nervous Breakdown is first and foremost an ensemble. It includes several well-known actors, but none of them is above the title on the marquee. This arrangement not only creates a sense of team spirit, but it also means that, even when an actor is out of a performance, an audience will still get plenty of star power.

So when Rachel Bay Jones did the part of Lucia three times earlier this month for Patti LuPone, who had prior commitments long since conveyed to potential ticket buyers, I suspected that Jones would experience less pressure than if she had, say, replaced LuPone in Gypsy. In a conversation the other day, Jones confirmed my supposition.

"Patti's are big shoes to fill," Jones said. "She's an exquisite force of nature. But there's so much star power in the show, and everyone is so supportive, that I had an easier time of it than I might have in another situation."

Not only did Jones, who grew up in Florida to parents who were actors, know well in advance she would have to go on those three times. She was prepped both by director Bartlett Sher, who, Jones said, gave her the freedom to make the role her own, and by LuPone. "Patti was so great," Jones commented. "She insisted that I hang out in her dressing room, and helped make sure that I had everything down." Jones also had three or four rehearsals before she went on. (If an understudy has to go on early in a run, often he or she has had no full, formal rehearsals at all.)

None of the above is to say that for Jones, who recently released a CD called ShowFolk, which brings a beautifully evocative folk/bluegrass flavor to eleven lesser-known Broadway tunes, playing Lucia wasn't a challenge.

"I've never understudied before," Jones said. "So the process of creating the character of Lucia for myself was a completely intellectual one, rather than getting it into my body and working it out."

Jones said that her first Lucia performance "was concentrated and very specific. I moved from spot to spot, wanting to make sure I did everything correctly." She continued: "On the second and third times, I could actually enjoy myself more. Lucia is such a fun part, with so many wonderful costumes."

And how did Jones find performing Lucia's big second-act number, Invisible, in which she tells the often sad story of the previous twenty years of her life since her husband, Ivan, left her? "It really challenges an actor to communicate all the emotions you need to convey in that song," Jones said. "It's a wonderful song, but it doesn't have the typical crescendos that musical theater often uses to convey a message. Everything has a lid kept on it."

There was no lid kept on things in Rent, a show that Jones did years ago in Berlin and that, because it was sung in German, I couldn't help quizzing her about as we concluded our conversation. "I don't speak German," Jones said, "so I had to learn all of the parts phonetically. For three weeks, I did almost nothing but put those songs in my head." Jones said she had forgotten most of the songs since (at least in German; she performs one of them, "Another Day", in English on her CD), with the exception of "Seasons of Love". Jones sang a bit of it to me in German. It was lovely, but I'll stick with the English!

Brendan Lemon is the American theater critic for the Financial Times and the editor of lemonwade.com.