Barcelona dropped points for the third time in four league games as they were held 0-0 by local rivals Espanyol in a heated Catalan derby on Saturday.
Atletico Madrid moved two points clear of Barca at the top of the table, having played a game more, thanks to substitute Thomas Partey's late winner to edge past Levante 1-0.
Real Madrid now trail Atletico by five points ahead of their trip to Valencia on Sunday.
Lionel Messi and Luis Suarez hit the woodwork for Barcelona either side of half-time, but Espanyol's physical approach was rewarded with a first point against Barca in eight matches.
"The result in general was fair based on what both teams created, although I thought we had a lot of chances," said Barca boss Luis Enrique.
Espanyol committed 22 fouls despite a lenient approach from referee Jose Luis Gonzalez, but Luis Enrique refused to blame the officials for a stuttering start to the new year.
"Football is a contact sport," he added.
"That is why we have a referee there to control the game."
The first of three meetings between the sides in 10 days got off to a frenetic start with Espanyol forcing Barca onto the back foot.
Their best chance came from a set-piece, though, when Alvaro Gonzalez's header was brilliantly stopped by Claudio Bravo and Gerard Pique hooked the ball to safety off the line.
Barca's star front three of Messi, Suarez and Neymar combined for 137 of a record 180 goals in 2015, but they didn't come to life until midway through the first half when Neymar's dangerous cross fell just behind Suarez.
Messi then struck the angle of post and bar with an almost perfect free-kick as Barca began to take control just before the break.
However, Espanyol had another chance to take a shock lead seven minutes into the second period when Hernan Perez poked a shot just wide after a lung-bursting run into the Barca box.
The hosts had another slice of luck when Suarez could only strike the outside of the post after rounding Pau Lopez and turning away from Gonzalez moments later.
Messi should have done better when he fired straight at Lopez when well placed on the edge of the area and the Espanyol 'keeper made another comfortable save from Neymar's acrobatic effort as they restricted Barca to surprisingly few clear openings in the final stages.
And the closest they came to a dramatic winner was another vicious Messi free-kick from long range that dipped inches wide of the target a minute from time as Barca failed to score for the first time in La Liga this season.
At the Vicente Calderon, Atletico's struggle for goals continued, but they were bailed out by an error from Levante 'keeper Diego Marino 10 minutes from time.
"Once again the changes gave us the quality we needed in the game, especially in the movement for the goal," said Atletico boss Diego Simeone.
Marino undid his good work earlier in the game as he got down brilliantly to turn Jackson Martinez's low drive to safety.
Atletico had a big claim for a penalty turned down when Angel Correa was clipped inside the area and Stefan Savic then headed against the bar as they pushed for the opener.
Simeone's men's luck appeared to be out when Koke unleashed a piledriver from Martinez's knockdown against the bar.
However, their persistence was rewarded when just as against Rayo Vallecano in midweek, Partey came off the bench to make the telling contribution as he skipped through the heart of the Levante defence but his shot ought to have been stopped by Marino as it trickled into the net.