Sergio Busquets admitted Barcelona are stuck in "a negative dynamic" after a 1-0 defeat to Rayo Vallecano that means they have lost three consecutive home games for the first time this century.
Alvaro Garcia's fine strike in the seventh minute condemned Barcelona to a Camp Nou loss, with Vallecano doing the double over the Catalan giants in LaLiga this season.
Barcelona had only suffered three straight losses at home once in their rich history, when Louis van Gaal's team experienced that disappointment in games spanning the 1997-98 and 1998-99 seasons.
Now they must pick themselves up from the bitter blow and go again next Sunday, when Real Mallorca will be their visitors.
Busquets said in a post-match LaLiga interview: "We're finding it really hard to win games at home at the moment. We've been conceding goals very early and that makes it even tougher for us, then you suffer a little bit more.
"Then the teams close up and defend the result. When you're not effective in both areas, it's a bit of a struggle as well."
Barcelona did not concede until early in the second half when losing 1-0 to Cadiz at home, but in their Europa League loss to Eintracht Frankfurt they were 2-0 down by the break, and it took two goals in second-half stoppage time to cut their deficit to 3-2 in that game.
Barcelona's latest defeat means they remain second in the Spanish top flight, albeit level on points with third-placed Sevilla, and Real Madrid's lead at the top is 15 points with five rounds of games remaining.
Madrid can clinch the title by avoiding defeat to Espanyol next weekend.
Captain Busquets said Barcelona attempted to add pace to their game in the second half, but they were largely flat and increasingly desperate as Vallecano manfully defended their lead.
Barcelona led the shot count 18-3, but only five of their shots hit the target. Their 71.3 per cent of possession counted for little come the final whistle as Vallecano became just the fourth promoted team to win both of their games against Barcelona in a LaLiga campaign, and the first since UD Salamanca in 1997-98.
"They were very well set up, we weren't effective," Busquets said. "When you don't score and the minutes go by, everything gets a lot tougher.
"We're in this negative dynamic at Camp Nou. We haven't been able to take advantage of the games we've had, and we've ended up level with Sevilla.
"Maybe in the second half we needed to put more attacking players on and go for the game. We had crosses in, we had chances, but it wasn't to be."