Ginardo announces the arrival of the Contessa d'Arco, who, as a result of a peace treaty, was promised in marriage to Corradino. He had immediately repudiated her, but was obliged to agree that he would not marry anyone else. The Countess has heard that Matilde is to be accommodated in the castle and intends to have her evicted. The women insult each other, and the resulting noise brings Corradino and his guards to the gallery (Quintet: "Questa è la Dea? Che aria!" - "This is the goddess? What a picture!"). Matilde stands firm, Ginardo and Aliprando are amazed that Corradino makes no attempt to kill her for her impertinence, and the Countess is further enraged. Corradino is confused - his head is spinning and his blood is burning. He asks Ginardo to look after Matilde, and departs with Aliprando. The Countess storms off, pursued by Matilde.