Barcelona's wobble continued as they lost a seven-goal thriller against Atletico Madrid at the Vicente Calderon to leave Pep Guardiola's side only four points clear at the top of the table.
Guardiola's men have now not won in the league in three games, following a previous draw with Real Betis and defeat to Catalan rivals Espanyol.
Thierry Henry fired Barca in front in spectacular, long-range style on 19 minutes and Lionel Messi added a second on the half-hour mark following a jinking run.
Atletico, though, came storming back as Diego Forlan blasted in on 32 minutes and Sergio Aguero equalised on 56 minutes.
Barca - who defeated Atletico 6-1 at the Camp Nou in October - reclaimed the lead through an Henry tap-in with just over quarter-of-an hour remaining, but an 80th minute Forlan penalty and another Aguero goal with 60 seconds left on the clock earned revenge for the home side.
European hopefuls Malaga suffered a shock 2-0 defeat at the hands of Recreativo, while Real Mallorca moved out of the drop zone with a 1-0 win over relegation rivals Sporting Gijon.
Malaga had been hoping to move into fourth place with a win over Recreativo, but the home side suffered a blow in the 35th minute when Manuel Ortiz Lolo was sent off for foul play and the Andalusians never recovered.
Recreativo took the lead via a Javier Camunas strike after half-time, before Perez Adrian Colunga added a second just beyond the hour-mark to seal the 2-0 win at La Rosaleda.
Meanwhile, Juan Arango scored the only goal of the game just after half-time to secure Mallorca a 1-0 over Sporting Gijon and lift the club towards safety.
The win moves Mallorca ahead of their relegation rivals on goal difference in what could prove a pivotal result come the end of the season.
Mallorca may have eased the pressure, but there was no such good news for rock-bottom Numancia, who stretched their losing streak to seven games with a 1-0 loss to Deportivo la Coruna.
Last year's Segunda Division champions had managed to hold out for 75 minutes against the visitors, but Juan Rodriguez's late winner moves Deportivo close to fourth-placed Villarreal, while condemning their opponents to yet another defeat.
Villarreal dropped points as they threw away a two-goal lead to draw at struggling Real Betis in Sunday's late kick-off.
A Santiago Cazorla brace (six and 36) had handed the visitors a comfortable lead at Estadio Manuel Ruiz de Lopera, but Betis hit back through Sergio Garcia (42) and star player Ricardo Oliveira (57).
Osasuna earned a hard-fought 1-1 draw with Racing Santander, but still descended into the relegation zone following Mallorca's win.
Los Rojillos made the short trip west and will have feared for the worst when Oscar Serrano gave the home side the lead after just 13 minutes.
But Walter Pandiani equalised for Osasuna on half-time, leaving the relegation candidates to dig in and secure a vital point.
Elsewhere, Almeria won the battle of the mid-table foes with a 2-1 win over Getafe at the Estadio del Mediterráneo.
Both sides had been on equal points at the start of the day, but an Alvaro Negredo brace following Joffre Guerron's eighth minute opener gave Almeria the three points.