David Moyes suffered a humiliating first defeat as Real Sociedad coach as his team were overwhelmed in the second half by a rampant Villarreal.
The visitors withstood the pressure until the 63rd minute when Bruno Soriano's free-kick came off the underside of the bar and bounced off the body of goalkeeper Enaut Zubikarai to roll into the net.
Denis Cheryshev added a second for Marcelino's men 10 minutes later and then substitute Moi Gomez scored two goals inside six minutes to make it 4-0 and pour more misery on Moyes, who had guided his troops to three clean sheets in his previous three games in charge of the Basques.
The Scot had to do without injured striker Imanol Agirretxe, midfielder Markel Bergara and centre-half Gorka Elustondo, but was able to recall Inigo Martinez and David Zurutuza, with Carlos Vela playing alone up front.
The Mexican scored a hat-trick in the 3-0 win over Elche last week but was isolated for most of the game and La Real were not able to register a single shot on goal in the first half.
Villarreal showed marginally more ambition in the first half but still struggled to break down the visitors.
Luciano Vietto had the best opportunity when he pounced on a slip by Martinez but shot over the bar from inside the box, while Ikechukwu Uche saw a shot saved at the near post by Zubikarai and Bruno hit a free-kick just over the bar.
Villarreal had more prupose in the second half and a goal for the hosts started to look inevitable as the lively Vietto created space to shoot on the edge of the area but saw his shot crash off the outside of the post.
A few moments later Bruno also hit the woodwork, striking his free-kick better than on the previous occasion, but enjoyed better fortune than his team-mate as the ball fell into the net off the back of Zubikarai.
La Real had a couple of half-chances, with Sergio Canales volleying on goal but failing to get enough power to beat Sergio Asenjo, who also saved comfortably from Vela.
At the other end, Vietto hit the left hand post yet again but Villarreal kept the attack alive and eventually got the second goal - Uche coming down the right and chipping the ball back across goal for Cheryshev to volley into the ground and in off the far post.
Uche's replacement Gomez had only been on the pitch for four minutes when he added the third, dispossessing Canales on the halfway line, spreading the play to Cheryshev and then hitting the Russian winger's crisp pass into the top corner.
And it was not long before the 20-year-old was celebrating again, Zubikarai letting the substitute's shot from the edge of the area slip through his hands and over the line.