Javier Gracia's Malaga headed into the match on a barren run having been knocked out of the Copa del Rey by Athletic Bilbao last week on the back of two league points from the past 12 on offer.
But Samu Castillejo headed the decisive goal in the 25th minute and Valencia only threatened sporadically thereafter - Javi Guerra coming close to doubling Malaga's lead five minutes later
Visiting goalkeeper Diego Alves reacted sharply to deny Sergi Darder in the 70th minute and Valencia's task became harder still when defender Joao Cancelo collected his second booking for fouling Nacho Camacho.
Malaga's Nordin Amrabat clattered a 25-yard strike against the inside of the upright, while Valencia's last sight of an equaliser came when Alvaro Negredo sent a volley bobbling wide from a similar distance.
Valencia sit fifth with 41 points - two places and six points better off than their conquerors on Monday.
