Barcelona's disappointing week took another bad turn tonight when they were held 1-1 by Deportivo La Coruna at the Riazor stadium.
Ronaldinho gave the Spanish and European champions a first-half lead from the penalty spot following a foul on Javier Saviola.
However, substitute Antonio Juan Rodriguez equalised for Depor when he knocked home a penalty rebound after Victor Valdes had saved substitute Fabian Estoyanoff's spot-kick.
Barcelona, whose 2-2 draw with Chelsea in midweek leaves them battling to stay in the Champions League, could now lose top spot, either to Sevilla or even Real Madrid if either of those clubs win on Sunday although Real would also need to improve their goal difference.
Real Sociedad are still without a win all season after they went down 2-0 to Levante.
New coach Miguel Angel Lotina got off to a losing start last weekend with a 1-0 defeat at home to Villarreal, and this week he earned his second consecutive loss at the Ciudad de Valencia.
Albert Meyong Ze and Laurent Courtois were the scorers for Juan Ramon Lopez Caro's team, who won for the first time in four outings.
Real Mallorca and Atletico Madrid played out a goalless draw in Palma.Reuse content