A masked ball is taking place at the palace in Madrid. Carlos is waiting in the Queen’s garden. A lady comes to the garden, wearing a mask, like everyone else. He thinks it is the Queen and tells her how he loves her. When the lady takes her mask off he realizes it is Eboli. She accuses him of loving the Queen. At that moment Rodrigue comes. He says to Eboli that Carlos is not well and does not understand what he is talking about. But Eboli is not deceived and plans to ruin their love affair.