Otello enters the room; Iago, pretending not to notice him, says that he is deeply troubled. Cassio sees Otello from afar and goes discreetly away. Otello asks what's wrong, but Iago gives only vague answers. Finally, he hints that Cassio and Desdemona are having an affair. Otello begins to get suspicious, but declares that he needs proof before believing that Desdemona has been unfaithful. (Iago, Otello: "Ciò m'accora... Che parli?" / "That worries me..." "What did you say?") Iago warns Otello against jealousy, but also advises him to be vigilant.