Real Madrid's hopes of retaining the La Liga title were dented Sunday as the champions lost 1-0 at Real Mallorca, to remain five points behind leaders Barcelona.
The Catalans host Sevilla later on and can open up an eight-point lead after a frustrated Madrid fell short against Javier Aguirre's side, with Marco Asensio missing a penalty against his former club.
Nacho's 13th-minute looping header into his own net separated the teams in a hard-fought clash, frequently slowed by various fouls from the hosts.
However Real Sociedad, third, could not cut their six-point deficit on Madrid as they lost 1-0 at home against Real Valladolid.
Amid a constant battle between winger Vinicius Junior and Mallorca's players and supporters, the islanders held off Los Blancos to record an impressive victory.
Vinicius suffered 10 fouls and Mallorca committed 29 in total.
"I think there's an atmosphere developing around Vinicius that doesn't favour anybody, not the player, not football, not the fans, who in the end get involved with the kid," Nacho told Movistar.
Real Madrid were without goalkeeper Thibaut Courtois, hurt during the warm-up, along with the injured Karim Benzema, Eder Militao and Ferland Mendy, among other absentees.
The match was heated from the start, largely due to historic bad blood between Vinicius and Mallorca.
Mallorca captain Antonio Raillo has criticised the Brazilian winger on multiple occasions for lacking respect towards opponents and said he wouldn't hold him up as an example to his son.
Home fans whistled Vinicius when he was on the ball and chanted Raillo's name.
Mallorca took an early lead when Nacho's attempted header sent Dani Rodriguez's in-swinging cross from the left looping over Courtois's stand-in Andriy Lunin and dipping just under the crossbar.
Nacho was under pressure from Mallorca target man Vedat Muriqi, who initially appeared to have scored the goal.
"It's been six games since I scored but I don't care that it's not mine, if we win, I don't care," said Muriqi.
The hosts shackled Vinicius well in the first half and reduced Madrid to pot-shots from distance.
Vinicius was booked for stepping on Pablo Maffeo's foot, leaving the Brazilian incredulous after various fouls against him had not been punished with a card.
- Heated -
Vinicius pulled at the Madrid badge on his shirt while looking at the home fans to agitate them further.
Early in the second half Raillo responded by offering Vinicius the Mallorca badge on his shirt to kiss.
"I think everything that is happening and has happened is not Vini's fault, Vini just wants to play football, and beyond that, there's an atmosphere of provocation. They foul him, that is what is happening," explained Madrid coach Carlo Ancelotti.
"Everyone thinks that it is Vini's fault but we have to look at the game, look at what happened today with him."
Madrid had a golden chance to level before the hour mark when Mallorca goalkeeper Predrag Rajkovic brought down Vinicius, but the Serbian denied Asensio from the spot.
Madrid will have to put defeat behind them quickly as they travel to Morocco midweek to take part in the Club World Cup.
"Now we have to think about the Club World Cup, we arrive with a lot of hope, with some difficulties, but we will manage it in the best way we can," added Ancelotti.
"After that we will come back, we want to fight for La Liga until the end, because here, it's not over yet, there are many games left and what happened to us today could happen in any game."
Real Sociedad did not profit from Madrid's slip-up as Canadian striker Cyle Larin netted his second goal in two appearances for Valladolid.
Imanol Alguacil's side had been unbeaten for seven consecutive games in the top flight but despite creating several chances they could not find the net.
Alexander Sorloth hit the post for the hosts and winger Takefusa Kubo also came close but Valladolid goalkeeper Jordi Masip was able to keep Real Sociedad at bay.
Earlier Valencia, 17th, fell to a 1-0 defeat at Girona, who kept their first clean sheet of the season.
Borja Garcia's goal consigned Los Che to their 10th defeat from 20 games, sitting just one point above the relegation zone.