Barcelona were held to a 1-1 draw at Deportivo La Coruna - four days after their 2-2 result against Chelsea.
Barca, who are battling to stay in the Champions League after facing the Blues, may lose the top spot in La Liga to Sevilla or Real Madrid on Sunday.
Ronaldinho's penalty gave Barcelona the lead after a foul on Javier Saviola.
Antonio Juan Rodriguez equalised when he knocked in a penalty rebound after Victor Valdes had saved Fabian Estoyanoff's spot-kick.
Sevilla or Real could go top of the Spanish table if they win against Osasuna or Celta Vigo respectively, although Real would also need to improve their goal difference.
Real Sociedad, who have yet to win this season, lost 2-0 to Levante, with goals coming from Albert Meyong Ze and Laurent Courtois.
Meanwhile, Real Mallorca and Atletico Madrid drew 0-0 in Palma.