Darren Criss of Glee Fills Daniel Radcliffes Shoes

Robert Caplin for The New York Times

Darren Criss, a sensation on Glee, is about to make his Broadway debut.

In a rehearsal studio off Times Square last week, Darren Criss a breakout star of the Fox high school musical series Glee was performing a bit too perfectly.

Preparing for his Broadway debut on Tuesday night as the corporate climber J. Pierrepont Finch in How to Succeed in Business Without Really Trying, Mr. Criss was leaping into the air during the number Grand Old Ivy and tucking in his feet as a dancer would. This drew a correction from the director, Rob Ashford, who wanted Mr. Crisss feet to be flat and extend sideways like those of an outstretched marionette, because his character should lack finesse.

What youre doing is almost too good, Mr. Ashford told Mr. Criss, who stood panting slightly in dress slacks and a blue T-shirt from his alma mater, the University of Michigan. A moment later Mr. Criss nailed the leap with precise imprecision.

There are few higher compliments on Broadway than being called a triple threat: a performer who can act, sing and dance to extraordinary effect. (Think of Hugh Jackman.) Mr. Criss is the latest to strive for this status, and the producers of How to Succeed are betting on him to an unusual extent. They are spending tens of thousands of dollars to rehearse and pay Mr. Criss for just three weeks of performances this month, before he returns to Glee, in hopes of molding him into a theater star they might build a Broadway musical around someday. (Nick Jonas of the Jonas Brothers will play Finch, the role held by Daniel Radcliffe of Harry Potter fame, from Jan. 24 through July 1.)

For Mr. Criss, this detour from Hollywood has been a moment to savor rather than a ticket to an ego trip. At 24, he exudes a perceptive maturity I was nobody a year ago, he said, so I want to make smart choices to keep the good things going with enviable self-confidence. You might almost consider him cocky if not for his strong tendency to poke fun at himself as he mentions his detailed knowledge of Star Wars minutiae or refers to himself (with his small, lean frame in mind) as a dainty dude.

I always shoot for the moon in my work, so that Im happy when I land on the roof, Mr. Criss said, a phrase he used twice during an interview at an Upper West Side diner. Im very specific and ambitious in plotting out my goals and never take no for an answer so its not like things just fall in my lap.

This three-week offer to play Finch, relatively rare for a newcomer to Broadway, is the latest height in a dizzying rise for Mr. Criss, who became a literal overnight sensation after his first appearance on Glee in November 2010.

In that episode Mr. Criss playing a gay member of a high school choir being eyed by a series regular sang vocals covering Teenage Dream, a pop hit by Katy Perry. Other Glee cast recordings had been released to success on Billboard charts, but Teenage Dream became a meteoric seller.

Soon the curly-haired, dark-eyed Mr. Criss was an idol, appearing solo in GQ (under the headline King of the High School Musical) and on People magazines Sexiest Men Alive list. This season he became a main character on Glee, a promotion he said he had no reason to expect a year ago.

Television fame remains a little surreal to Mr. Criss, given that he grew up in San Francisco, working in theater! . He app eared in plays more than musicals as a teenager and college student, developing a love for commedia dellarte in Goldonis Servant of Two Masters and notching an early romantic role as Peter van Daan, the love interest of the title character in The Diary of Anne Frank.

At the University of Michigan, a training ground for Broadway singers like Gavin Creel and Hunter Foster, Mr. Criss said he had never done a musical until he wrote one with friends. A Very Potter Musical, their parody of the Harry Potter books and movies, became a cult hit on campus; a filmed performance has drawn millions of views on YouTube, and Mr. Criss and his collaborators soon formed their own theater company, StarKid Productions, in Chicago.

In between Glee shoots last season, he wrote the music and lyrics for the companys musical called Starship, which he referred to as my baby. It ran at the Hoover-Leppen Theater in Chicago last winter, drawing mixed reviews from critics but gathering a fan following on StarKids YouTube channel. (His moxie extends to the hope of seeing Starship or another StarKid show on Broadway in the next five years.)

Starship was typical of the four or five projects that Mr. Criss said he had going at one time, relying on e-mail and iPhone applications to help him stay working beyond Glee land. In fact, he described his eight-performances-a-week schedule in How to Succeed as the easiest thing Ive done in a while, in the best sense, compared with Glee shoots that can begin at 6 a.m.

This lifestyle isnt so different from when my mom drove me from theater rehearsal to soccer practice to violin lessons in a single day, said Mr. Criss, whose boyish face was masked by mo! dish bla ck-rimmed glasses and the light beard he often grows when hes away from Glee.

Even though he looked different from his Glee character, Blaine Anderson, a succession of fans came over in the diner to ask for autographs, including three tween girls from Buenos Aires who were briefly dumbstruck when he asked how to spell their names.

Mr. Criss credited his parents with giving me a sense of humility and the good judgment about how to spend every day. Those instincts, he said, led him in 2010 to meet with the film and theater producers Craig Zadan and Neil Meron, who were impressed with his Glee work.