"I am very sorry that I will not be able to come to Philadelphia for performances as Norina this season," Netrebko said in a statement issued through the OCP. "I am completely exhausted and need time to rest. Most importantly, I do not wish to perform for the wonderful audiences of the OCP if I am not the very best I can be, which is what all opera audiences deserve."

Sari Gruber, who has sung the role of Norina with the Boston Lyric Opera, agreed to step in for Netrebko at short notice. The rising American soprano has appeared with the New York City Opera and Lyric Opera of Chicago, but does not have the star power of Netrebko.

OCP artistic director Robert Driver expressed exasperation in an interview with the Philadelphia Inquirier. "It's a 'mea culpa' that I'm paying the bill for," Driver said, adding that the production had been planned as a showcase for Netrebko. "This [production] got put on the books because of Netrebko ... we asked her, 'What do you want to do?' "