A 2-2 draw down in Huelva late on Saturday leaves Barcelona practically out of the Spanish title race. ( dpa )
Samuel Eto'o scored two for Barca, but Argentine striker Marco Ruben struck back with two goals for Huelva.
Barca have won just four of their 16 away matches, and have picked up just two points in their last three games.
The disappointing draw leaves them with 60 points from 32 games, six points less than leaders Real Madrid, who are at home to lowly Murcia on Sunday.
Barca are just one point above third-placed Villarreal, who are away to Almeria on Sunday.
Eto'o put injury-plagued Barca into the lead after just two minutes, heading in a perfect centre from Giovani Dos Santos.
As so often this season, though, the Catalans lacked the authority to build on their lead. In the 41st minute, Huelva were awarded a controversial equalizer, despite Ruben's header having been stopped by keeper Victor Valdes on the goal-line.
Eto'o restored Barca's lead in the very first minute of the second half with a blistering long-range drive.
But Frank Rijkaard's team again failed to close down the game and again allowed Huelva to equalize, with Ruben taking advantage of a slip by Valdes to make it 2-2 with another header.
Barca looked weary and resigned to their fate at the end.
The draw leaves Huelva fifth from bottom with 37 points, well placed to avoid the drop.
Earlier on Saturday Racing Santander had moved up to joint fourth by winning 2-1 away to crisis club Valencia.
It was a poor way for Valencia to warm up for Wednesday's King's Cup final against Getafe.
The only good news for "Los Ches" was the return to action of Spain striker David Villa, who came off the bench and scored with a calm penalty.
Santander had deservedly gone ahead in the 61st minute through Gonzalo Colsa, who put away the rebound after Valencia keeper Timo Hildebrand had kept out his header with the help of the post.
Just two minutes later Valencia were given a clear penalty when Aldo Duscher clumsily pulled down veteran Fernando Morientes - and Villa made no mistake from the spot.
The equalizer animated Valencia and their long-suffering fans, and Morientes twice hit the woodwork in a frenetic finale.
However, Santander were not prepared to settle for a draw. Nine minutes from time, Pablo Alvarez centred from the right for Mohamed Tchite to make it, despite a strong suspicion of offside.
Marcelino's Garcia's hard-working team now have 53 points and are level with Atletico Madrid, who are away to Valladolid on Sunday.
Santander and Atletico are five points ahead of sixth-placed Sevilla.
As usual, Valencia were jeered off by their long-suffering fans. They have won just one home game in five months, and remain seventh from bottom with just 39 points.
Only a cup final win can now save unpopular coach Ronald Koeman from the sack.