He was performing alongside Natalia Osipova in the Royal Ballet’s Giselle in London when he somehow hurt himself (no details were given) early in Act One. While he finished the act, he did not return to the stage after intermission. “Mr. Hallberg returned to the stage just 14 months ago, after a two-and-a-half-year injury-filled break and a painful, painstaking fight back to physical prowess. (Dancing with Ms. Osipova again, he has said, was one of his strongest motivations.)”