Fabregas knows Spain will not have things all their own way against Paulo Bento's side, with it difficult to tell how a game brimming with creative talent will play out.
He said: "Portugal will be very difficult. They have strong individuals, strong players.
"Apart from their good open play, they are very good on the counter-attack, and we'll have to work hard in that game.
"They have (Cristiano) Ronaldo, Nani, Raul Meireles, Joao Moutinho. They have very good players."