Leo Baptistao haunted his parent club Atletico Madrid by scoring the only goal in a Villarreal victory at El Madrigal which took Marcelino's side top of the Primera Division.
The Brazilian has not played for the Rojiblancos since September 2013 but made them regret letting him go out on loan to Villarreal by firing low into the corner after 14 minutes to earn the 1-0 win.
Atletico had an opportunity to go ahead of title rivals Barcelona and Real Madrid but came unstuck against an excellent Villarreal side, and created few notable chances to equalise. They remain on 12 points while Villarreal climb to the Primera Division summit with 16 points.
Visiting boss Diego Simeone opted to start Jackson Martinez instead of Fernando Torres alongside top scorer Antoine Griezmann, but it was Villarreal's front two of Roberto Soldado and Baptistao who proved more effective.
For the all-important goal, Manu Trigueros played the ball to Baptistao in the area and the Brazilian turned to play a one-two with Soldado and arrow his shot into the bottom corner.
Former Tottenham striker Soldado could have scored a goal of his own not long afterwards, but his arrowed shot was saved by Atletico goalkeeper Jan Oblak. The Slovenian was beaten later in the half by Samu Castillejo's header, but the former Malaga forward's attempt went just wide of the near post.
An otherwise passive Atletico created just one clear chance before the break, a long punt forward which Griezmann managed to control but could not steer past goalkeeper Alphonse Areola.
Simeone made a double change at half-time by bringing on former Villarreal striker Luciano Vietto and Torres, the two players who scored the goals in the 1-1 draw here last season, while Marcelino withdrew goalscorer Baptistao for 18-year-old Matias Nahuel.
It was another substitute, Angel Correa, who had Atletico's best chance to equalise in a tight second half.
The Argentinian played a one-two with Griezmann before going for goal but his shot was beat away by Areola, allowing Villarreal to claim a fifth straight win and the league leadership.
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