A late Umar Sadiq earned the draw for Los Che after Villarreal had led through Pape Gueye.
Corberan said afterwards: "We have a lot of work ahead of us. I like the things I see from the team. I don't want us to have to take a step back.
"In the first few weeks of work I could see the players' desire and anger at where they were. They were committed to going out and achieving the objective. The key is to keep up the fight constantly and for them to recover from the blows.
"This marathon never stops. We are going to fight in every game.
"Today, in general, I liked those who started and those who came off the bench. Without the contribution of those who come off, it is impossible to win or draw games. We need everyone at their best. We need maximum commitment. We need a large group, committed and dedicated.
"After the pain of those who went to Barcelona, the people continue to believe in us and that increases our responsibility. I can only thank the people for their dedication."