Ibai and Victor Camarasa struck first-half goals as Alaves recorded a surprise 2-0 victory at high-flying Villarreal in La Liga.
Winger Ibai slotted in from close range with eight minutes played after Deyverson's header came back off the left post following a right-wing cross from Edgar.
The fourth-placed hosts, who created little throughout the game, could have fallen further behind when Theo Hernandez struck the left upright from the edge of the box.
Midfielder Camarasa, on loan from Levante, doubled the advantage in the 19th minute, seizing on some woeful defending by Argentinian Mateo Musacchio to poke the ball past Villarreal goalkeeper Sergio Asenjo.