Fiorenza sang with Maria Callas as early as 1957 in Gluck's Iphigénie en Tauride, and many times later, until Callas' last Norma in Paris.
"Later, Callas, at the end of the second act, said to me, 'Fiorenza, stay tonight until the end because I am not well, and we will all go out [to take curtain calls and bow] together.'