A brilliant strike by Santo Ezquerro gave ten-man Athletic Bilbao a surprise 2-1 win over Barcelona.
Bilbao had lost their last seven games at the Nou Camp, and last season were thrashed 7-0.
Barcelona could have gone top if they had won the game.
Barcelona looked a shadow of the side which beat Liverpool in the Champions League on Tuesday.
They were without the suspended Philip Cocu and the injured Luis Enrique Martinez. Rivaldo was left on the bench due to a temperature and a slight thigh strain.
Ismael Urzaiz's tenth-minute header put Bilbao in front. Rivaldo equalised after 58 minutes.
Bilbao centre back Jesus Maria Lacruz was handed a second yellow card in the 74th minute, before Ezquerro scored the winner with nine minutes to go.
The defeat leaves the Catalan club in third place on 23 points, trailing leaders Deportivo de La Coruna by three points, although they could be overtaken by Valencia and Betis following today's games.
Bilbao, who have the division's best away record with five wins out of seven matches, are fifth, also on 23 points.