"After musical rehearsals began, all parties agreed that the part had changed dramatically and Mr. R‹hlig agreed to withdraw from the production," the release read. "San Francisco Opera believes strongly in Mr. R‹hlig as an artist and has offered him a role in a production in a future season."

It is the second major cast change for the opera, which opens on October 1. Kristine Jepson replaced Lorraine Hunt Lieberson in the role of Kitty Oppenheimer in July because Lieberson is suffering from a back injury.

Doctor Atomic is based on the life of physicist J. Robert Oppenheimer, who directed the Manhattan Project, the American effort to develop an atomic bomb. It takes place in 1945, in the days leading up to the first detonation of the weapon. Baritone Gerald Finley sings the title role in the world-premiere performances.

The cast will also include tenor Tom Randle as Robert Wilson, baritone James Maddalena as Jack Hubbard, bass Eric Owens as General Leslie Groves, mezzo-soprano Beth Clayton as Pasqualita, and tenor Jay Hunter Morris as Captain James Nolan.

Peter Sellars, who collaborated with Adams on Nixon in China and The Death of Klinghoffer, is the director. San Francisco Opera music director Donald Runnicles will conduct. Ian Robertson will direct the chorus.

Lucinda Childs, who collaborated with Adams and Sellars on Nixon in China, is the choreographer. Adriane Lobel, a veteran of Broadway and opera, is the set designer. The design team also includes Dunya Ramicova (costumes), James F. Ingalls (lighting), and Mark Grey (sound).

The design, according to a release, consists of "atmospheric representations of the New Mexico desert, the extreme intensity of the workrooms, and the spartan home life of Kitty and Robert Oppenheimer. Both the secrecy and the sense of government-issued thrift about the Manhattan project are telegraphed through discrete uses of materials and mechanics: in one scene change, laboratory-ceiling rafters become perimeter fences guarding the labs."