Real Madrid lost 3-0 to Recreativo Huelva at home in a game overshadowed by the deaths of four visiting supporters in a bus crash.
Recreativo players pay tribute after the deaths of four of their fans
Florent Sinama-Pongolle, on loan from Liverpool, scored for Recreativo.
Sevilla are guaranteed top spot in the Primera Liga over Christmas after a 4-0 win over Deportivo La Coruna.
Former West Ham and Tottenham striker Frederic Kanoute scored twice to give his side a four-point lead over Barcelona, who play on Thursday.
At the game in Madrid, Sinama-Pongolle opened the scoring when he held off Fabio Cannavaro before firing past goalkeeper Iker Casillas.
The Real team, which included David Beckham and Ronaldo in its starting line-up, fell 2-0 behind when Ikechuckwu Uche stormed past Guti and Cannavaro to score.
Midfielder Emilio Viqueira added the third in injury time with a well-placed free-kick.
"Matches before the holidays are very dangerous," said Real coach Fabio Capello.
"We didn't look the same team that played Espanyol at the weekend. The whole team was non-existent."
Real are third, five points behind the leaders, while Real Zaragoza, Valencia and Atletico all have 27 points.
The match at the Bernabeu was preceded briefly by sombre music and both teams wore black armbands in tribute to the four supporters who died and the 35 who were injured on their way to the game.
Four bouquets of flowers were laid on the field before kick-off and Real said that ticket proceeds from the match will be donated to the families of those killed and injured.
Meanwhile, Real Betis recorded a 1-0 victory at bottom club Gimnastic Tarragona, thanks to Marcos Assuncao's 65th-minute penalty.
Osasuna recorded their seventh successive win with a 2-1 victory over Levante, who had former Newcastle winger Laurent Robert sent off.
Espanyol captain Raul Tamudo scored his seventh goal of the season to help his side to a 1-0 win over Getafe, Racing Santander beat Villarreal 2-1, while Real Sociedad drew 0-0 at Celta Vigo.