Villarreal sacked coach Jose Molina after their 1-0 defeat at Levante in La Liga on Sunday, having taken only one point from their last five matches.
A replacement, who will be their third of the campaign, has yet to be named, the struggling east-coast club said in a statement.
Former goalkeeper Molina had only been in the post since December when he was promoted from the B team to replace Juan Carlos Garrido.
Villarreal lie 17th in the standings with 27 points and are only three points above the relegation zone with 11 matches left to play this season.
They finished fourth last termto qualify for the Champions League but lost all six group games as their campaign started to unravel.