Kirchschlager and Netrebko were slated to sing the roles of Idamante and Ilia respectively, in three performances of the opera on September 14, 17, and 19.
Netrebko, citing a heavy schedule this summer promoting her new CD and DVD, asked general director Plácido Domingo to release her from the production. Angelika Kirchschlager withdrew because of exhaustion after recent appearances at the Salzburg Festival.
Kate Aldrich, playing Idamante, and Adriana Damato, performing Ilia, will now sing all seven performances of the opera. Plácido Domingo and Allan Glassman will share the title role of Idomeneo.
The production opens Wednesday, September 8, and will run through September 26.