Joan Sutherland singing in Hugarian (Fledermaus Czardas) 

Strauss II - Die Fledermaus (in English), San Francisco 1973 & San Diego 1980 (with Beverly Sills on cast).
Joan as Rosalinde.
Funny anedocte about Joan in this operetta:
When doing Die Fledermaus, Joan decided that since her character - Rosalinde - is impersonating a Hungarian when singing the 'Czardas', she would learn the aria in Hungarian. She and her prompter Susan Webb worked tirelessly until they got it just right. Joan brought the house every night. However, San Francisco's preeminent music critic, who often disparaged her, blithely wrote in his review "As usual Sutherland's diction, she might as well sung the Czardas in Hungarian". The fact is he had no clue. Joan's reply to the critic "But sir, I was singing in Hungarian!".
True Tales from the Mad, Mad, Mad World of Opera by Lofti Mansouri, p.107.
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