Elsewhere, Villarreal hammered Girona 5-0 at home as new signing Tajon Buchanan netted a hat-trick to open his La Liga account.
A second-consecutive defeat to start the season leaves Girona, who played Champions League football last season, bottom of the table with seven goals conceded and none scored.
“When you don’t compete at 100 percent, a team of Villarreal’s calibre will run you over,” said Girona coach Michel Sanchez.
“That’s what happened. We play for the pride and respect of the people and we didn’t do the job we should have done.”
The home side raced into a 4-0 lead inside 30 minutes, with Nicolas Pepe and Rafa Marin scoring as Buchanan grabbed a brace.
The Canadian then got his third four minutes after the hour to cap a scintillating performance by the Yellow Submarine.
Real Sociedad fought back from being 2-0 down at half-time in the Basque country to earn a point against Espanyol.
Pere Milla and Javi Puado gave the Catalans the lead, before Ander Barrenetxea and Orri Oskarsson hit back for Sociedad in eight second-half minutes.
Ante Budimir’s ninth-minute goal gave Osasuna a 1-0 win over 10-man Valencia.
