NEW YORK: In a rehearsal room near Times Square recently, Tyler Lea was learning how to fight dirty.

The young actor who has now made his Broadway debut in "The Curious Incident of the Dog in the Night-Time" was practicing grappling with his onstage father.

The two men grabbed each other tightly and each tried to wrestle the other to the ground, but the brawl was going too seamlessly for choreographer Steven Hoggett.

"Messy, messy, messy," Hoggett advised gently, adjusting their arms and torsos into angry positions. "It will look like a duet if you're not careful."

Making the fight scene more scrappy was just one thing Lea learned on this day. He also jumped, slid, crawled, played with a toy airplane, winced as a rat seemed to run across his shoulders and pretended to be an astronaut in zero gravity.

It was all part of stepping into the Tony-winning play about a 15-year-old with autism named Christopher. Last week, Lea took over the role from Alex Sharp, who won a best-actor Tony.

"I've never, ever done anything like this before. I don't think I ever will again," Lea said afterward. "What I think I'm doing mostly is trying to get into Christopher's brain to see how he sees the world."

For Lea, 27, a talented and soft-spoken graduate of the University of North Carolina School of the Arts, it's a huge step. His biggest credit so far has been at the Cygnet Theatre in San Diego.

He'd been working as a waiter for the past few years, serving drinks and hors d'oeuvres at cocktail parties, waiting for his big break. A grueling round of auditions this summer resulted in a starring role at the Barrymore Theatre.

"It's taking me some time to get used to the idea that it's real," he said. "When it actually happens, you go, 'Oh, this is really happening. This is it.'"

The play — based on an adaptation of Mark Haddon's best-selling novel — is a swirling, beautifully kaleidoscopic series of scenes that includes evocative movements and projections of constellations, complicated city maps and terrifying escalators.

"It's about difference. It's not really about an autistic boy, necessarily. It's about someone who sees the world differently," Lea said. "It's about difference and how I overcome that."

To anyone in the autistic community who might be unhappy with a non-autistic actor playing an autistic role on Broadway, Lea is apologetic.

"I'm trying to bring as much truth to it as possible," he said. "I don't want to offend anyone — that's not the purpose of the play I don't think at all."

During the rehearsal session, Lea was game for all the show's physicality, bounding around a carefully taped-out grid on the floor wearing knee pads, sneakers and a blue hoodie.

Tony nominee Hoggett, who created the play's movements with Scott Graham, said the young actor's physicality and narrative skills are excellent, and that he's a perfect successor.

"Actors can sometimes say, 'Yes, I've got it,' but they just want to please you. But he's got it. He's genuinely got it in his body," Hoggett said.