Real Sociedad continued La Liga's unpredictable start to the season by going top of the table on Sunday, after a 3-0 win away at Real Betis.
Villarreal had temporarily claimed first place earlier in the day by beating Valencia 2-1 at la Ceramica but Real Sociedad's impressive victory put them ahead on goal difference.
They are the sixth different team to lead La Liga after six rounds of fixtures so far, as Real Madrid gave up their place at the top of the pile after a surprise loss at home to Cadiz on Saturday.
Barcelona were also beaten away at Getafe.
Real Sociedad took advantage as Portu and Adnan Januzaj scored goals either side of Mikel Oyarzabal converting a penalty to consign Betis to a third defeat in four games under their new coach Manuel Pellegrini. They drop to sixth.
Earlier, Dani Parejo came back to haunt Valencia by scoring the winner for Villarreal, against his former club.
After making 363 appearances for Valencia, many of them as captain, Parejo was one of a handful of key players allowed to leave in the summer.
His deflected shot in the 69th minute was a reminder of what they were missing as Villarreal held on to go one point above Real Madrid.
Despite a 4-0 thrashing at the hands of Barcelona last month, it has been an encouraging start for Unai Emery, who was appointed Villarreal coach in July.
They have 11 points from their first six games.
Valencia sit 12th, having won just once in their last five matches, with the future of coach Javi Gracia still uncertain.
Gracia was critical of the club after Valencia sold the likes of Parejo and Francis Coquelin to Villarreal, as well as Rodrigo and Ferran Torres to Leeds and Manchester City, but failed to make a single addition in the summer transfer window.
Emery was also once at Valencia and so was Villarreal's Paco Alcacer, who opened the scoring with a penalty before Goncalo Guedes levelled shortly before half-time.
Yet Parejo had the last word, receiving a pass from Takefusa Kubo and curling in after his shot deflected off Mouctar Diakhaby. Kubo was then sent off in the 90th minute after coming on in the 64th.