Real Madrid suffered a shock 1-0 defeat to relegation-battling Rayo Vallecano at the Estadio de Vallecas on Sunday.
Adri Embarba's 23rd-minute penalty put the hosts ahead, and they were then fairly comfortable as they held their narrow lead to the final whistle against a much-changed and poor Real side.
Zinedine Zidane's team have now won just two of their last six matches in La Liga and sit nine points behind second-placed Atletico Madrid.
Rayo, meanwhile, moved themselves off the bottom of the table with the victory but still sit six points from safety with three games of the season remaining.