Anton Haizinger heard Haizinger sing in concerts, and offered him an engagement at the theatre; Haizinger gave up teaching. Haizinger's first roles at Theater an der Wien, in 1821, were in two operas by Rossini, as Gianetto in "La gazza ladra" and Lindoro in "L'italiana in Algeri". He soon became well-known in Vienna. The role of Adolar in Weber's opera "Euryanthe", premiered in 1823 at the Theater am Kärntnertor, was created for him, and he was a soloist in the premiere in 1824 of Beethoven's Ninth Symphony at the same theatre. He continued studies with Antonio Salieri. At this time, Italian opera
La forza del destino (1867). Following these productions, Verdi made further, more extensive revisions to the opera with additions to the libretto by Antonio Ghislanzoni. This version, which premiered at La Scala, Milan, on 27 February 1869, has become the standard performance version. The most important changes were a new overture (replacing a brief prelude); the addition of a final scene to Act 3, following the duel between Carlo and Alvaro; and a new ending, in which Alvaro remains alive, instead of throwing himself off a cliff to his death. The opera in this version is frequently performed in the world's opera houses today.