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.
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.