Real Sociedad put one foot into next season's Champions League with a 1-0 win over 10-man Almeria on Tuesday in La Liga.
Takefusa Kubo's first-half strike gave Imanol Alguacil's side, fourth, an eight-point lead on fifth-place Villarreal, who face Cadiz on Wednesday.
Almeria striker Luis Suarez was dismissed after 36 minutes for a rough tackle on defender Robin Le Normand.
Japanese winger Kubo, in fine form, took his goal brilliantly, cutting in from the right and curling into the top left corner in first half stoppage time.
Alexander Sorloth could have doubled La Real's lead late on but fired narrowly wide, while Ander Barrenetxea hit the post.
Real Sociedad have not played in Europe's premier competition since the 2013-14 season and can qualify if Villarreal fail to win any of their last three matches or by earning two more points themselves.
Defeat leaves Almeria provisionally 15th, four points above the relegation zone.
Celta Vigo, 14th, were held to a 1-1 home draw by Girona and are five points above the relegation zone.
Later Tuesday champions Barcelona visit Real Valladolid, who are 18th and battling for survival themselves.
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