Ms. Hall-Tompkins said that the show always made her think of Alfred Mur, an elderly neighbor she befriended who was a violinist and a Holocaust survivor, and who died a few years ago. She was so taken with his life story that she published his memoir as an e-book, and is planning a paperback edition. “I can’t help but think that there’s a little bit of Alfred in all this,” she said.

This is also the Broadway debut for the other fiddler — the one who dances, and occasionally seems to fly, onstage. Mr. Kovarsky, who took violin lessons as a child, said that as he danced he wanted to mime the playing realistically, but not so much so that audiences would forget that someone of Ms. Hall-Tomkins’s caliber was actually playing the music.

“As a dancer, it’s such an honor to physicalize the music, to represent the music that’s there,” he said.

Mr. Kovarsky had another high-profile, wordless role last year when he played one of the terrorists who kill a disabled Jewish passenger on a cruise ship in John Adams’s “The Death of Klinghoffer” at the Metropolitan Opera — a production that drew protests from some Jewish groups. Now he is playing one of the pre-eminent symbols of Jewish pop culture, the fiddler in “Fiddler on the Roof.”

“It was an interesting road, to go from there to here,” he said.

The two fiddlers can’t see each other during the show, so they worked together to make their playing seem to match. Mr. Kovarsky learned how to mime a mean vibrato, and Ms. Hall-Tompkins gave him pointers on inflection, bowing and movement.

As the show begins each night, Mr. Kovarsky has a little song to help him remember the bowings (the direction of each stroke) for the opening melody. “In my head I keep singing, ‘Up do-own up up down; u-up up down up down,’” he said, as Ms. Hall-Tomkins joined in.

One challenge was how Mr. Kovarsky could convincingly pretend to play without making ugly, distracting sounds that his microphone would pick up. The props department tried fishing line instead of violin strings; a bow with a ribbon where the horsehair should be; violin strings kept very loose. All involved trade-offs. Now he uses plastic strings, muted with felt.

The two fiddlers said that they enjoyed their symbiotic relationship as they shared the audio and visual aspects of the title role. “That’s the real opportunity here — not to mimic violin playing so much, but to embody the idea, the impression, the stylized, mythical side — just like the Chagall painting,” Ms. Hall-Tompkins said. “The heightened expression of it.”