When the rows of showgirls at Jubilee! kick their slender legs in unison, with every thread of their elaborate costumes perfectly in place, or when Celine Dion floats onto the Colosseum stage, her entire appearance famously flawless down to the smallest detail, no one in the audience is thinking about anything other than the razzle-dazzle.

But backstage, a team of dressers is on high alert, ready to handle any wardrobe malfunction, no matter how big or small, as they orchestrate each and every costume change. These nimble wardrobe masters must do whatever it takes to ensure that every performer hits the stage wearing the perfect costume.

“Dressers have a high-pressure position,” says Christie Moeller, a Las Vegas fashion stylist and blogger. “They have to know the show inside and out—one missed cue can throw the entire show out of whack. It’s imperative that they be quick on their feet and can MacGyver a broken zipper at a second’s notice. They are the unsung heroes of a stage production.”

One company has this backstage costume choreography down to a science: Cirque du Soleil, which currently has seven shows on the Strip (eight by spring). Because of the acrobatic quality of the shows, the performers must have each piece of clothing tailored or custom-made, from headpieces to shoes, for safety reasons. A team of attendants stands at the ready backstage making sure everyone gets their precise costumes put together, which is no small task given all there is to keep track of.

“At Love alone, 4,800 costume pieces are run around backstage every night (in 358 individual costume concepts), plus 110 wigs,” says Jowee Geary, wardrobe attendant for Cirque’s The Beatles Love. “Plus, each outfit has both an English and a French name,” says Sandra Fox, Love’s head of wardrobe. “There’s also the character’s name and the name of the guy wearing it."

Dressers organize the costumes and help with quick changes during the show, often doing a full change in a tiny space in minutes or less. They also oversee the costumes, from colorful Cirque-made unitards and reworked wrestlers’ shoes, to the designer wear of the A-list headliners, such as the red-soled Christian Louboutins that are Holly Madison’s shoe of choice in Peepshow, and the outlandishly stylish getups of Elton John. “Elton’s costumes are awesome, and all of his band wears Dolce & Gabbana,” says John Stone, the wardrobe head at the Colosseum at Caesars Palace.

A dresser’s schedule can be grueling. In many cases, only night owls need apply. “I get to work at seven and get all of the presets ready for the first show,” says Duane Cosner (aka Shaun Wayne), assistant head of the wardrobe department at Jubilee! “Then there’s a ‘lunch’ break before the second show starts at 10:30, and I stay until 2 AM.”

It wouldn’t be theater without backstage drama, and even when productions are mapped out to the finest detail, live theater is predictably unpredictable. Every dresser has a story or two of a backstage emergency, whether it’s using thread to sew in loose cornrows, or jumping over a monorail wall to find black silk socks for a star minutes before the show is about to begin. “Something will always need to be fixed,” Stone says. “That’s the nature of the job. Just when you think you’re about to walk into an ordinary day, it becomes unordinary very quickly.”

Unlike at the Cirque shows, the Colosseum has an ever-changing rotation of productions—starring A-listers who can be notoriously particular, and who often come with personal dressers who the Colosseum staff must then seamlessly work into their routine. “We’re constantly focused on who’s leaving and coming back and what the crews require,” Stone says. “Elton’s leaving, Celine’s coming back. I’m like an air traffic controller.”

Dressers to the headliners, in particular, form a close connection to the star they are charged with outfitting night after night, often for years.

“Some days at the end we all sit around and talk, like a girls’ moment,” says Denise Soteras (better known as Zorba), Celine Dion’s personal dresser and costume production supervisor for all of Dion’s performances. “We really have a lot of fun doing what we do. She’s incredibly funny, always joking and laughing. After each show I’ll talk about what worked and what didn’t work. I’ll start to give my excuses, and she’ll say, ‘Don’t ever do that, don’t apologize.’ Yet, if you’re getting her into a robe and her elbow hits me, she’ll ask, ‘Are you OK? Are you sure?’”

Now retired, Anne Pierce has dressed a plethora of stars, including Mac Davis, Steve Lawrence and Eydie Gormé, Barry Manilow, Shirley MacLaine, Joan Rivers, and Diana Ross, who once demoted her on the spot because she was wearing eyeglasses around her neck that Ross called “distracting” when they reflected a stage light. “What I loved about being with Joan [Rivers] was that you didn’t sit around during the day,” Pierce says. “We’d go shopping, or sailing on Lake Tahoe. You saw things. With the others you didn’t.” The respect was mutual: “Anne Pierce was one of the great ones,” Rivers says. “In her day, to have her dress you was a way of having arrived, just as having a Bob Mackie gown or Nelson Riddle arrangements did. It meant, ‘I’m a headliner.’”

Rivers, of course, toured the country for decades doing stand-up, so is especially adept at having a dresser for her stage performances. “They know what your body really looks like,” she says. “They know who you see and who you’re ‘out’ with. They know what secrets you’ve said on the phone to whom. They know your most intimate habits.”

Tracy Bohl, now the wardrobe supervisor at Peepshow, remembers working with theater legend Michael Crawford, the original Phantom in Phantom of the Opera. “I always brought someone with me, because he wants to entertain,” she says. “They would laugh at his jokes, so I could get my work done.”

Before a performer makes it to the level of Michael Crawford or Diana Ross, they often lean on their dresser for support, especially if they’re away from home. “I have 15 girls, French girls, Russian girls, and they can be very young,” says Eva Liden, head of wardrobe for MGM Grand’s Crazy Horse Paris. “They ask what doctor I go to, what is this in the pharmacy. As much as I’m a dresser, I’m also a mother and a psychologist; I don’t just put their costumes on and zip them up. They’ll get dressed up after the show and ask, ‘Is this appropriate to go out?’ and I always say, ‘You look beautiful.’”