David Moyes admitted his Real Sociedad side could have lost by a heavier scoreline as Villarreal ended his unbeaten start in Spain with a 4-0 win.
Ex-Manchester United boss Moyes earned four points from two La Liga matches, plus a Copa Del Rey draw at Real Oviedo, in his opening three games.
Sociedad had not conceded a goal in any of those matches, but capitulated against Villarreal in Sunday's defeat.
"It could have been more, we could have lost more goals," said the Scot.
"We made some terrible mistakes, defensively bad mistakes, especially with the third and fourth goals."
Sociedad registered just two shots on target against sixth-placed Villarreal as they dropped to 14th in the Spanish top-flight.
"In the first 20 minutes of the game we had some opportunities, but not enough," said Moyes.
"We knew we were coming to a difficult ground and we wanted to be hard to beat, and for 50-60 minutes we were, but in the end it was not good enough."
The Basque side, who are three points above the relegation zone, face local rivals Athletic Bilbao at home on Sunday.