La Real's hopes of reaching the Europa League knockout round is now in the balance after Thursday's 3-1 defeat.
Oyarzabal said afterwards: “It was a night to forget, everything came together for us. Nothing went our way and the expulsion conditioned everything for us. But it was a very bad day, in which they were superior.
"We ask for forgiveness for the part that affects us and we can start from scratch, we have to try to get over this as soon as possible.
“I would like to apologise to all the people who came, who have been supporting the team from the beginning to the end.”
He added: "We are alive, we need to win the last match to ensure our qualification and the good thing is that we have it at home, with our fans, where we have been strong lately, we will try to make sure that victory falls on our side.”