Relegated Elche surprise Atletico with rare win
Leaders Barcelona can win the title later on Sunday with a win at city rivals Espanyol and Atletico, third, can no longer catch them.
Atletico, who have been in sensational form since the World Cup, were inexplicably blunt against bottom-of-the-table Elche, who earned only their fourth win of the season.
Fidel Chaves broke the deadlock in the 41st minute, when Atletico goalkeeper Ivo Grbic badly flapped at a throw-in, leaving the winger with an open goal.
After Real Madrid beat Getafe on Saturday they overtook Atletico by two points.
Earlier Valencia snatched an important late victory at Celta Vigo to climb provisionally to 14th, three points above the relegation zone.