Real Madrid coach Zinedine Zidane felt his side had let two points slip away as Gerard Moreno's late penalty earned Villarreal a 1-1 draw at Estadio de la Ceramica.
Los Blancos were out to get their LaLiga campaign back on course following a 4-1 defeat at Valencia before the international break.
Mariano headed the visitors into an early lead but Real Madrid, missing captain Sergio Ramos through an injury picked up with Spain, could not build on their advantage.
Villarreal, who were looking to go top of the table, created several good openings before there were awarded a penalty with 15 minutes left.
Substitute Samuel Chukwueze was brought down by Real Madrid keeper Thibaut Courtois and Moreno dispatched the spot-kick.
"We deserved much more from today's performance, especially in the first half. I'm annoyed as the boys worked really hard and we dropped two points," said Zidane, whose side sit fourth in the standings.
"We have to praise my players, they did well, we controlled the game and in one move they equalised. That can happen in football.
"We had a chance today to pick up three points and it's a shame (that we did not hold on)."
Zidane also brushed off questions over criticism coming his way from a lack of consistent results.
"I have the same drive and it will always be like that until the last day," he told a post-match press conference, reported on the Real Mardid club website.
"You continue with what you are doing and I will get on with my work."
Eden Hazard made a first appearance since November 3 following a positive Covid-19 test.
Zidane was pleased to see the Belgian playmaker, who went off after 65 minutes, back in action.
"He has not played for a long time and in a match you have to manage the minutes well, but he is involved and he is fine," the Real Madrid coach said.
Zidane also played down reports Isco had asked for a transfer when the window opens again in January.
"He is a Real Madrid player, he is staying here and that's it," the Frenchman said. "We are not going to talk about what happens inside (the club), that stays inside."
Villarreal continued their unbeaten home form, but manager Unai Emery felt his side had created enough chances after falling behind to take all three points.
"In the second half we have accumulated four clear chances to score and they only had one," the former Arsenal boss said, as quoted by Spanish media outlet Marca.
"Drawing with the league champion can leave you satisfied, but when you look at what happened over the whole 90 minutes, I have the feeling that the game should have been ours.
"That does not deviate us from our path, from our idea of what we want to do, but my satisfaction is reduced because I think we deserved to win."
Emery added: "What I want is stability in our growth, gaining credibility and confidence.
"The ambition and demand that I impose on myself makes me believe that we have left two points today, and that leaves us not satisfied.
"However, we are taking the right steps and on the way to growing."