The cocktail of choice for Elisabeth Moss these days is very post-"Mad Men."

"It's close to 5:30, isn't it?" she asks a waitress at a chic bar in the theater district one recent afternoon.

"I'll do a vodka ginger ale, please. A little light on the vodka."

No Don Draper-style whiskey sours or martinis for Moss, who has left her beloved character Peggy Olson to play the title character in "The Heidi Chronicles" on Broadway.

Today's drink is as much a pick-me-up as a way to unwind after a long day of rehearsal. Moss, whose features and personality are softer and lighter in person than the buttoned-up Peggy, admits she's only recently found out what she's signed up for.

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"It's physically far more challenging than I thought it was, mentally far more challenging. I don't know why I didn't realize that," Moss said.

"I'm like, 'Wow. Ballsy move, Moss. You really took on something bigger than you've done before. But that's what I want to do."

The play is a series of sketches stretching over 24 years from the late 1960s to 1989 that playwright Wendy Wasserstein uses to trace Heidi Holland's changing ideas about herself, about men and about other women.

Moss, 32, had known of the play, which won a 1989 Pulitzer and a Tony for best play, but she hadn't read or seen it. The mix of comedy and drama instantly attracted her: "It's my favorite thing to do — to do both in one thing."

She's a stage veteran, having made her Broadway debut in "Speed-the-Plow" with Jeremy Piven in 2008 and most recently starring with Keira Knightley in Lillian Hellman's "The Children's Hour" in London in 2011.

She and Tony Award nominee Bryce Pinkham, who stars in the play as Heidi's best friend, have bonded over Broadway shows and genuinely like each other. It helps that Pinkham has been impressed by his co-star's onstage skills.

"The thing about Elisabeth is she's really one of those actors that, when you watch her, you kind of get a little angry," he said with a laugh.

"It's sort of like watching somebody paint with watercolors. It's like, 'How are you doing that?' and 'How do you know how to do that?' and 'How did you know it was going to look like that when you finished it?' And yet somehow it feels effortless and peaceful the way she does it."

TV viewers fell in love with Moss' Peggy aboard "Mad Men," watching her go from lowly secretary to copywriter to advertising star. But the actress said she had no idea where creator Matthew Weiner was taking her.

"That fact of becoming a strong moral compass and becoming someone who had a voice and telling that story of feminism in the workplace — I had no idea," she said.

The end of "Mad Men" — the last few episodes air in April — has been looming for some time, but Moss said she was still pretty emotional by the last day of filming.

"It sounds so silly because obviously you never want to equate the ending of a show with something that's actually dramatic and emotional — like life. But we'd known each other for nine years and the only thing I can equate it to is how you might have felt when leaving four years of college," she said.

"You have to say goodbye properly, and I think that we did say goodbye properly. I felt like when I left that night, I felt ready to move on. I felt I had done whatever I needed to do to move on."

Moss and her two dogs have relocated permanently to New York, and she's been on a tear watching as many Broadway shows as possible before her own nights are busy onstage.

She's seen "If/Then," ''The Curious Incident of the Dog in the Night-Time" and "A Delicate Balance." She also rushed to see Tony Award winner Jessie Mueller in the Carole King musical "Beautiful" for a specific reason.

"I wanted to see someone who was good on Broadway," said Moss, with a laugh. "Like, 'That's what's good. Try to do something like that.'"

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