Villarreal midfielder Dani Parejo scored the decisive goal in a 2-1 win at home to former club Valencia to take his side top of La Liga on Sunday.
Parejo, who used to captain Valencia but switched to Villarreal in August, saying he had been forced out, barely celebrated his goal after his shot took a heavy deflection off Mouctar Diakhaby into the net in the 69th minute.
Paco Alcacer, another former Valencia player, had given Villarreal the lead with a penalty in the sixth minute although Goncalo Guedes levelled for the struggling visitors in the 37th.
Villarreal had Japan international Takefusa Kubo sent off in added time for a second yellow card while Parejo then limped off the pitch with a muscle injury.
Yet Unai Emery`s side saw out the win to lead the standings on 11 points after six games, one ahead of second-placed Real Madrid who were beaten 1-0 at home by Cadiz on Saturday.
Valencia were left 12th on seven.