Description on Youtube:
Mozart's "La clemenza di Tito" at Salzburg Opera Festival, 2003, with Michael Shade (Tito), Vesselina Kasarova (Sesto) and Dorothea Röschmann (Vitellia). This is Vitellia's aria from Act I "Deh, se piacer mi vuoi". Vitellia's part is incredibly demanding, and Ms. Röschmann sings it brilliantly.
If you like this piece, go buy the DVD, it's worth it!