Real Madrid's la liga title hopes were dealt another huge blow as they suffered a third league defeat in five games to Roberto Soldado's solitary goal at Villarreal.
Atletico Madrid's 2-1 win over Athletic Bilbao earlier in the day means Real now trail their city rivals and Barcelona by five points at the top of the table.
Real were outplayed in the first-half on Sunday, but reacted after the break and were left to rue a hat-trick of missed chances by troubled French striker Karim Benzema as defeat piles the pressure on under-fire coach Rafael Benitez.
Real had won five consecutive games since being thrashed 4-0 at home by Barca last month, but were forced onto the back foot by a whirlwind start from Villarreal.
"I am not happy at all with the first half and I think the reaction in the second half is the route we have to follow," said Benitez. "Unfortunately, today it has cost us three points."
Jonathan dos Santos had already smacked the inside of the post before Soldado turned home Cedric Bakambu's pass against his old club on eight minutes. Bakambu had two great chances to double Villarreal's advantage before half-time, but the Congolese striker pulled his shot wide when clean through on Keylor Navas before firing over from inside the area.
Having been dominated in the first half, Madrid came out a different side after the break and had a series of chances to turn the game on its head.
Benzema had scored five times in his last two outings for Madrid despite his off-field problems which saw him indefinitely banned from playing for France in midweek, however his range was off as he volleyed inches wide from Gareth Bale's through ball.
Another fine Bale cross was blasted over by Benzema moments later before Bale had a great chance himself, but on his weaker right foot didn't have the power to beat Alphonse Areola in the Villarreal goal.
At the Vicente Calderon, Atletico were forced to come from behind as they conceded for just the seventh time in 15 la liga games this season when Aymeric laporte swept home Benat Etxebarria's corner. Saul Niguez headed in the equaliser close to the break and in sceond half Antoine Griezmann's stunning strike from 25 yards secured three points.
Elsewhere, a late own goal salvaged a point for Valencia in Gary Neville's first taste of la liga action as los Che battled back with 10 men to draw 1-1 at Eibar.