Natalia Osipova burst into tears on her first day of play rehearsals. "I cry. I'm shaking. I'm stressed and completely lost on the first day," the Royal Ballet principal says of preparing for her first ever acting role. "I think, 'I'm a piece of shit!' I want to take a taxi and run away."

She did not run away. By the second week of rehearsals, Osipova was still in the room, working through the part that brought her to the stage: Lydia Lopokova, the Russian ballerina who danced with Diaghilev's Ballets Russes and, in 1925, unexpectedly married the British economist John Maynard Keynes.

The play is James Graham's The Standard of Living, with Keynes as its protagonist, directed by Nicholas Hytner. Its themes, the Guardian reports, include taking risks and imagining a brave new future — a description that maps neatly onto Osipova's own leap from ballet to spoken drama. The cast is led by Rory Kinnear.

Lopokova herself was no stranger to hostile receptions. Keynes's Bloomsbury circle dismissed her, in one of the harsher judgments of the age, as a "frivolous foghorn of a chorus girl." Osipova has found a personal resonance in that history. Entering Hytner's rehearsal room alongside a cast of established stage actors, she says, she felt like Lydia among Keynes's sneery Bloomsbury friends.

"I left rehearsal and cried," she says, "because I feel, 'Oh my god, I'm so bad.' But you learn and listen and every day, step by step, I do better."

The move into theatre was not something Osipova engineered on her own. She demurred when former colleague Edward Watson suggested she audition. His response was blunt: "You're stupid! You need to try because it's amazing opportunity."

She took the advice. The result is a career pivot that, on her own account, returns her to what drew her to ballet in the first place. "Maybe I'll never be super perfect for classical ballet because I love stories so much," she says. Acting, she suggests, sits closer to the core of her artistry than pristine technique.

There is also a linguistic bridge between performer and character. Osipova, a Russian dancer who previously requested a translator for interviews, now speaks English in what the Guardian describes as an idiosyncratic gallop — a rhythm, the paper notes, not unlike Lopokova's own. The historical ballerina, a Russian in Bloomsbury, endured condescension partly on the strength of how she sounded; the contemporary ballerina, entering an English rehearsal room, has faced a version of the same outsider's test.

The physical details of the interview carry their own quiet symbolism. A delicate silver necklace shines beneath frank brown eyes — the ballerina, famed for her ferocious jump and dramatic intensity on stage, sitting for interviews as a debutante actress still finding her footing.

Osipova remains a principal of the Royal Ballet, one of the most watched dancers of her generation. The Standard of Living marks her first professional speaking role, and the trajectory from shaking first-day despair to "step by step, I do better" suggests the risk-taking the play itself celebrates. If Osipova carries Lopokova's story to the stage with anything like her usual conviction, the theatre world may be hearing considerably more from her.