Santiago Solari was handed a nightmare start as permanent Real Madrid manager after his side lost 3-0 at Eibar.
Goals from Gonzalo Escalante, Sergi Enrich and Kike ended Madrid's run of four straight wins, condemning them to their fifth league defeat of the season.
Madrid spurned the chance to move up from sixth in the table and climb to within a point of league leaders Barcelona, who were in Madrid to face Atletico later on Saturday, while Eibar climbed from 13th to seventh ahead of the weekend's other matches.
Madrid remain sixth and miss the chance to move to within a point of league leaders Barcelona, who are away to Atletico this evening, while Eibar climb from 13th to seventh.
Eibar looked to attack Madrid from the off, as Kike's looping half-volley was tipped onto the post by Thibaut Courtois after three minutes.
Seconds later, Gareth Bale thought he had given Madrid the lead with a half-volley of his own, but it was ruled out for offside.
A frantic opening 10 minutes was not showing any sign of slowing down, as Karim Benzema's shot from close range was cleared off the line.
With 16 minutes gone, Eibar took the lead through Escalante. Marc Cucurella, on loan from Barcelona, led a counter attack following a sloppy Madrid corner with his cross finding Kike, and though his shot was saved by Courtois, Escalante was on hand to score the rebound.
Bale had a curling free kick from just outside the box saved by Asier Riesga later in the half, but Madrid failed to create any more chances of note before the interval.
Six minutes into the second half, Madrid's problems worsened as Eibar doubled their lead. Cucurella robbed Alvaro Odriozola of possession, squaring the ball to Enrich who finished calmly.
Madrid's woe went on as Eibar made it three after 57 minutes. Cucurella was again given time and space to cross from the left wing, and Kike nipped in front of Sergio Ramos to tap it in.
Courtois had to produce a fine save from Fabian Orellana to deny Eibar a fourth, before Kike saw his effort go just wide.
Benzema had a couple of openings as Madrid's half-hearted search for a comeback looked to take off, but Eibar were never really threatened and were able to comfortably see out the win.