Lionel Messi celebrated his record 506th appearance for Barcelona in La Liga by scoring a penalty but the Catalans could only draw 1-1 with Cadiz on Saturday.
Messi's spot-kick looked likely to secure a narrow win for his side. But Barca failed to score a second despite a handful of chances and Cadiz punished them with a late equaliser, Alex Fernandez converting from the spot after a wild swing from Clement Lenglet.
The draw means Ronald Koeman's side move only one point closer to Atletico Madrid in the table instead of three, after Atletico gave their rivals an opportunity by losing at home to Levante.
Barcelona had won their previous seven games and another victory would have put them within touching distance of Atletico.
Instead, Koeman will look back upon a disappointing week for his team, that also saw them hammered 4-1 by PSG on Tuesday.
Player ratings for Barcelona players from the match can be seen in the picture gallery above. To view the next image, click on the arrows or swipe if on a mobile device.