Rivera has become an Adams specialist over the past year or so. She created the central role of Kumudha in his most recent opera, A Flowering Tree, in Vienna and San Francisco, and she filled in for Dawn Upshaw in performances of his El Niê±o with the Boston Symphony last December.

In addition to the casting of Rivera, Lyric Opera also announced that contralto Meredith Arwady will portray Pasqualita, the Oppenheimers' Mexican housekeeper, in Doctor Atomic. A third-year member of Lyric's Ryan Opera Center for young artists, Arwady recently won a $10,000 Richard Tucker Foundation Career Grant.

Doctor Atomic, in the same staging by director Peter Sellars that ran in San Francisco, will receive eight performances from December 14, 2007 to January 19, 2008 at the Civic Opera House in Chicago. Robert Spano will conduct; Baritone Gerald Finley will play J. Robert Oppenheimer, with baritone Richard Paul Fink as Edward Teller, bass Eric Owens as Gen. Leslie Groves, baritone James Maddalena as Jack Hubbard and tenor Thomas Glenn as Robert Wilson (the physicist, not the director).