Zinedine Zidane's decision to rest Cristiano Ronaldo backfired as Real Madrid suffered a shock 1-0 loss away at Espanyol on Tuesday.
Gerard Moreno was the hero for the hosts, slamming home a half-volley deep into injury time, as Quique Sanchez Flores' side recorded their first victory over Madrid since 2007.
Ronaldo had scored eight goals in his last two trips to the RCDE Stadium but Zidane opted to leave the Portuguese forward at home, no doubt with next week's Champions League second leg against Paris Saint-Germain in mind.
Minus their top scorer, as well as the influential midfield trio of Casemiro, Toni Kroos and Luka Modric, a much-changed Madrid struggled for fluency against opponents they have recently put to the sword.
The Spanish champions saw their run of five wins in all competitions come to an unexpected end at a venue that has seen LaLiga's heavyweights struggle this season.
Having already held runaway leaders Barcelona, as well as inflicting Atletico Madrid's solitary league defeat so far in the campaign, Espanyol stunned their illustrious opponents with Moreno's dramatic winner.
All eyes were on Gareth Bale to provide the firepower for Madrid, yet he couldn't mark his landmark 116th LaLiga appearance - equalling David Beckham's record for a British player in the competition - by finding the net.
The Welshman had his team's best chance in the contest, sending a close-range header straight at Diego Lopez, who reacted quickly to palm the ball down before gratefully collecting the rebound, in the early stages.
But the visitors failed to build on their positive start, turning in a below-par performance that leaves them in danger of losing third place to Valencia before the weekend.
They were fortunate not to fall behind in the first half when Raphael Varane's loose pass led to an opportunity for Moreno, only for Espanyol's top scorer to fluff his lines when clean through. His right-foot effort was judged to have missed the target completely, with the officials failing to see a clear deflection off goalkeeper Keylor Navas.
The forward did hit the target soon after, though, only for his effort to be chalked off. The decision looked tight, though the moment further energised an Espanyol side growing in belief.
Sergio Garcia tested Navas from a ridiculously tight angle early in the second half before Oscar Duarte's header from the resulting corner looped onto the top of the crossbar with the goalkeeper beaten.
At the other end, Achraf Hakimi and Mateo Kovacic both saw ambitious long-range attempts held easily by Lopez as Madrid were forced to try their luck from distance.
Zidane threw on Karim Benzema and pushed Sergio Ramos forward in the hope of finding a breakthrough in the closing stages, yet the bold move only allowed Moreno to capitalise on the extra space in the Madrid defence to expertly convert Garcia's cross from the right.
