Iraola said: "I think it probably gives them the advantage of knowing that if they are not at their level, we can surprise them.
"I don't think it is going to be the case anymore, so we have to show that we can do it again. We have the advantage of playing at home, but it is going to be difficult because they are a very good team with very good players.
"You have to keep the concentration over 100 minutes with them because if we make a mistake, normally they score."
On Marcus Tavernier's injury, he said: "I hope he can play the last games, but it is true that it is going to be difficult. If everything goes well, he could be available for us for the last two games, or something like this."
Iraola added: "It is tough when someone like Tav (Marcus Tavernier) gets a muscle injury and is out for four or five games. But it is something that is happening to all of the teams and we have to accept it."