International recognition came in 1965, when she appeared in a concert performance of Donizetti's "Lucrezia Borgia" at Carnegie Hall in New York City as a replacement for an indisposed Marilyn Horne. The performance won her great acclaim from the public and critics alike, and it made her an overnight sensation. Her success led to her first performance at the Metropolitan Opera that same year as Marguerite in Gounod's "Faust". 