Lionel Messi has marked his club record 506th La Liga appearance for Barcelona with a goal - but there were few celebrations after the Catalan giants drew 1-1 with Cadiz.
The visitors snatched a late penalty at the Nou Camp to deal Barca another setback in their bid for the title, at the end of a difficult week for Messi and his team.
Five days after being beaten 4-1 by Paris Saint-Germain in the Champions League, Ronald Koeman's side saw two points slip away when substitute Alex Fernandez converted an 88th-minute penalty conceded by Clement Lenglet.
Yet after Messi had scored from the penalty spot in the 32nd minute, it seemed as if they would stroll to victory.
Instead, they were unable to finish off their many scoring chances.
The draw now leaves Barcelona in third place, eight points behind leaders Atletico Madrid and five behind Real Madrid.
"These are two hard blows this week," Barcelona defender Gerard Pique said.
"There is a way to go in the league, but we didn't count on this. If we can get on a good run of play and get good results, we can still have a shot. It is going to be difficult."
Cadiz upset Barcelona 2-1 in early December when Koeman's side were still finding their way under their new coach.
Since then, Barca haven't lost in the league and were on a seven-game winning streak going into the Cadiz game.
It was Cadiz's first point earned at the Nou Camp since 1978.
Elsewhere, Aleksander Isak scored three goals to lead Real Sociedad to a 4-0 rout of Alaves.
David Silva assisted on Isak's second goal and again for Portu to round off the victory with a fourth goal.
Spain striker Gerard Moreno scored as sixth-place Villarreal drew 1-1 at mid-table Athletic Bilbao, while last-place Huesca beat ninth-place Granada 3-2 despite a missed penalty by Rafa Mir.