Flórez's first big breakthrough came in 1996, at the Rossini Festival in the Italian city of Pesaro, Rossini's birthplace. At the age of 23, he was asked to sing the leading tenor role in "Matilde di Shabran" when Bruce Ford became ill. He first sang at La Scala in the same year as the Chevalier danois in Gluck's "Armide". His Covent Garden debut followed in 1997 where he sang the role of Count Potoski in the world premiere of Donizetti's "Elisabetta". Debuts followed at the Vienna Staatsoper in 1999 as Count Almaviva in "Il barbiere di Siviglia" and at the New York Metropolitan Opera in 2002, again as Count Almaviva. On February 20 2007, the opening night of Donizetti's "La Fille du régiment" at La Scala, Flórez broke the theater's 74-year-old tradition of not having any encores when he repeated the aria "Ah! mes amis" with its nine high C's after the audience gave him an enormous ovation.