Pep Guardiola's side came into the match six points behind Madrid following the challengers' win against Granada yesterday but were hoping to cut the gap back to three by beating their lowly neighbours this evening.
They looked on course to do so as Cesc Fabregas gave them a 16th-minute lead but after failing to build on the opener, Barca - who also had efforts correctly ruled out for handball and offside - conceded the equaliser with less than five minutes to go as Alvaro Vazquez dived to head home.
Gerard Pique hit the bar with a late effort and Espanyol survived a penalty appeal for handball as Barca were left frustrated.
“The truth is that we are too well accustomed to how games go, but our rivals are also there to play. Espanyol did a fantastic job. In general, within the context of tonight’s difficult match, we controlled the match a bit better in the second half, even though we were a bit off target. After the equalizing goal, we reacted correctly, but it was too late. I cannot be dissatisfied with this team, I could never be,” said Guardiola.