Barcelona followed up their Champions League win over Manchester City in midweek with a potentially damaging 3-1 defeat at Real Sociedad that ensured Real Madrid ended Saturday three points clear of them at the top of La Liga.
Alex Song's own goal was cancelled out by Lionel Messi, who became the third-highest scorer in Primera Division history. With 229, he's one ahead of Real legend Raul.
For once the Argentinian couldn't spur his team on, and just as Messi missed out to Real's Cristiano Ronaldo in the race for the Ballon d'Or, Barca's chance of relinquishing their title to their biggest rivals increased.
It also signals a bad end to a week in which the club was investigated over its signing of Neymar from Santos.
Earlier, Real had thrown down the gauntlet with a 3-1 win over Elche that featured a first Primera Division goal for Real from 23-year-old Asier Illarramendi - signed from Real Sociedad for $44 million in the summer.
If he and Real's other two goalscorers Gareth Bale and Isco represent the future, a three-point gap does not mean this Barca generation can be consigned to the past despite slipping slightly from the high pedestal they have placed themselves on.
But after their midweek triumph, defeat hands more ammunition to critics such as Chelsea manager Jose Mourinho, the former Real coach who said last week that Barca had their "worst team in a long time".
Sociedad's second straight win came as 22-year-old Frenchman Antoine Griezmann scored after 54 minutes thanks to an assist from Mexican international Carlos Vela, before Griezmann set up David Zurutuza for the third five minutes later.
They go fifth, three points clear of Villarreal in the hunt for European places.
|Illarramendi scored his first La Liga goal for Real Madrid since moving from Real Sociedad last summer [AFP]
"We didn't feel comfortable or hold possession, which is our strength," Barca's Spanish national defender Gerard Pique said.
"This meant that they had openings.
"Now we have a break for a week and we can consider what went wrong. We are only three points behind so it isn't worrying."
Barca, who also had coach Gerardo Martino dismissed at half time for complaining to the referee, have 60 points from 25 matches.
Real lead the way on 63 points but Atletico Madrid can drawl evel with them by winning at Osasuna on Sunday.
At the Bernabeu, Illarramendi gave Real the lead before the break butit took them until the 72nd minute to score again with a rocket of a long-range drive by world-record transfer Bale that smashed in off the crossbar.
Isco, who arrived from Malaga in the same batch of summer signings as Bale and Illarramendi, added a third goal with nine minutes left.
Real were without leading scorer Ronaldo, serving the final game of his three-match ban, and without the Portugal forward they lacked spark in front of goal against an Elche side that defended solidly, with Bale somewhat anonymous before his strike.
"Bale didn't have confidence before scoring his great goal,and after that he was totally different," Real coach Carlo Ancelotti said.
"I am satisfied because we didn't concede. Our play could have been better but at this stage of the season we need to be solid and we were."