Franco Farina will replace Giordani in the role of Mario Cavaradossi, opposite Deborah Voigt's Tosca, on April 22, 26, and 29 and May 5 and 8. Another singer, yet to be named, will replace him on May 11.
Eduardo Villa was already scheduled to sing Cavaradossi on May 16, with Aprile Millo as Tosca.
The much-anticipated staging, which marks Voigt's first Tosca at the Met, also stars James Morris as Scarpia; Carlo Rizzi is the conductor. The production is by Franco Zeffirelli, with costumes by Peter H. Hall; Paula Williams is the stage director.
Giordani is next scheduled to appear at the Met's farewell gala for outgoing general manager Joseph Volpe on May 20. His spokesperson said, "Marcello is hoping to come back for the Volpe gala and will do everything he can to be there for it."