Barcelona stumbled to a 3-2 home loss against Valencia on Saturday, giving Atletico Madrid a chance to move into sole possession of first place in La Liga.
• Ledwith: Slack defending costs Barca
Barcelona's decision not to sign a defender during the January transfer window may have backfired after Valencia took advantage of a lethargic, uninspired effort from the home side at the Camp Nou.
Barca led through Alexis Sanchez's eighth-minute goal, but Dani Parejo equalised for Valencia before the break.
Lionel Messi set up the opener after slashing a pass across the box beyond the far post where Alexis connected oddly to float it over goalkeeper Diego Alves.
Valencia took control from the 44th minute when Parejo exploited a turnover inside the Barcelona half to lead a breakout with Sofiane Feghouli, who returned a pass inside the area for Parejo to score easily.
The diminutive Pablo Piatti headed Valencia ahead after the restart before Lionel Messi's penalty levelled the game again.
Messi's goal was his 10th in the league this season but first since Sept. 28 against Almeria.
But Barcelona's defence was dormant five minutes later as Feghouli moved around three players to the goal line before cutting back to meet Paco Alcacer, who blasted past goalkeeper Victor Valdes for the winner.
Barcelona played with 10 men from the 78th minute after Jodi Alba was shown a second yellow card.
Barca's defeat means Atletico can take over sole possession at the top of the table for the first time this season if they do not lose at home to Real Sociedad on Sunday, when Real Madrid can also overtake their greatest rivals with a victory at fourth-place Athletic Bilbao. Atletico and Barcelona are level on 54 points, while Madrid have 53.
Malaga rallied to beat Sevilla 3-2 as Duda proved the hero at Rosaleda Stadium.
Duda took advantage of Alberto Moreno's silly clearance attempt to gather inside the area and lift the winning goal past goalkeeper Beto in the 82nd minute.
Duda's penalty put the hosts ahead after half an hour before Sevilla scored a pair of unanswered goals through Carlos Bacca's 10th of the season and Federico Fazio's header in the 66th minute.
Samuel Sanchez pegged home the equaliser in the 77th minute as Malaga rallied for an emotional victory during which coach Bernd Schuster was red-carded in stoppage time.
Rayo Vallecano avoided defeat for the first time in three league games by drawing 0-0 at Levante, but remained in deep trouble in the Primera Division relegation zone.
This was an evenly matched game at the Ciutat de Valencia stadium which saw few openings until a frantic final 10 minutes, but neither team were able to take any of their chances.
Getafe were the width of a post away from earning a much-needed win against Real Valladolid had to settle for a 0-0 draw that hardly helps either side.
Six defeats and a draw in their last seven competitive matches had seen Getafe tumble down the Primera Division standings and crash out of the Copa del Rey, but that dismal winless run looked set to come to an end as Diego Castro's thunderous second-half stoppage-time strike arrowed towards the top corner.
However, the 25-yard effort crashed against the post and stayed out, and soon afterwards the full-time whistle went to leave Getafe and Valladolid -- who had also struck the woodwork early on -- still in trouble near the foot of the standings following a goalless draw.