Pape Guaye had Villarreal ahead before Umar Sadiq struck late an equaliser.
Marcelino said afterwards: "We lost two points in a predictable move. We knew that it was the main source of goals for the opponent. We did not defend well. We lost two points.
"I think we deserved to have won. At home again we conceded in the final stretch. It happened to us before. I am satisfied with the defensive level shown. In attack we had chances to score the second goal. The team transmits positive feelings.
"Dominating an opponent for 90 minutes is very difficult. I don't remember them having more than one goal-scoring chance. We didn't suffer at all. I think that with the adverse result they pushed forward their line of pressure. We had enough control to have won. It's not that the opponent dominated us and the match was super controlled, but any mistake you can make... in this part of the competition they are very accurate.
"We have to try not to concede. They have always scored against us in the final stretch. We have to pay extreme attention in those final minutes. I can remember some points that we almost won and we lost. This is a long-distance race. We have to get more points at home than in the first half. What really weakens you is losing. We played against Valencia at their best."
On Valencia's relagation prospects, he added: "I don't think so and I don't want it to. I say this because I love them and because I feel them. That team and those fans have to be in the Primera Division. Let's see if they take good care to return to their normal habitat and after getting the points to save themselves, they don't repeat this situation that happened two seasons ago."