It’s the moment they’ve all been training for.

Aaron Pegg has been photographing people on the subway for two years as part of his ongoing @underground_nyc Instagram series, but ballerinas are one of his favorite subjects.

“It’s such a great contrast between two art forms — the gritty subway with the elegance of ballet,” says the Lower East Side resident, whose subjects include dancers Brittany ­Cavaco (kicking it at Canal Street), Kelly Kakaley and Ingrid Silva. “I love working with ballerinas because they’re perfectionists. They make you want to be a perfectionist as well.”