In 2005 he told the British newspaper The Observer that he dreamed of singing Boccanegra before he retired. After that, he told the paper, "I will probably say Amen."
The lower depths won't be entirely new territory for Domingo, who sang as a baritone at beginning of his career in 1959. He began singing tenor when he joined the Mexican National Opera the following year and has since sung more than 120 opera roles on stage and in recordings.