Real Madrid's title challenge unravelled on Wednesday night as they suffered back-to-back defeats with a 2-1 loss at Sevilla.
Fresh from their clasico beating by Barcelona, Carlo Ancelotti's men still held the upper hand in the title race ahead of this game.
But another loss, coupled with wins elsewhere for Barca and Atletico Madrid, means they are now three points off the pace with their destiny out of their hands.
Goals from Neymar and Lionel Messi meant Barcelona kept the pressure on title rivals Atletico and Real Madrid with a comfortable 3-0 win over Celta Vigo but the evening turned sour when Victor Valdes was carried off with a serious knee injury that could end his Barca career and rule him out of the World Cup.
The goalkeeper struggled to hold on to a free-kick from Fabian Orellana midway through the first half and landed on his right knee as he gathered the ball, and was seen crying as he was taken off the pitch, replaced by Sergio Pinto.
It could be Valdes' last appearance for the club, with the player set to depart Barcelona in the summer when his contract runs out.
Diego Costa's solitary goal lifted Atletico Madrid back to the top of the Primera Division standings as they claimed a 1-0 win over Granada.
Costa headed Jose Sosa's cross past Granada keeper Roberto to ensure Atletico moved one point clear of Barcelona, who slipped to second, and three clear of capital city rivals Real Madrid.
A late penalty from Joaquin Larrivey condemned Osasuna to a fifth straight defeat at the hands of fellow strugglers Rayo Vallecano, who gave themselves a cushion to the relegation zone in a 1-0 win.
A drab match with little quality on display seemed destined to finish goalless until Abella Damia felled Jose Fernandez in the area and Larrivey stepped up to place his spot-kick in the bottom left-hand corner of the net.
The result will see Rayo climb several places in the congested lower reaches of the table, while Osasuna hover just above the drop zone, knowing they will drop into it if either Getafe or Real Valladolid can pick up a result on Thuesday.