Real Madrid's dismal season went from bad to worse when Cristiano Ronaldo scored an own-goal to hand relegation-threatened Granada a shock 1-0 win on Saturday.
Real coach Jose Mourinho had already given up winning the league before Christmas and this latest blow means that Barcelona can increase their lead over them to 18 points if they win at Valencia on Sunday.
There were doubts over whether or not Ronaldo would play as he is struggling with an ankle injury and his mood didn't improve when he headed a Granada corner into his own goal after 22 minutes.
Real had scored nine goals in their last two league games but they lacked the necessary drive perhaps as a result of a draining El Clasico in midweek where they scraped a 1-1 draw in the first leg of their King's Cup tie with Barcelona.
"It was not a good game and we lost and I am responsible," said Mourinho.
"I didn't like the first half from the team, it was terrible. We improved after the break and we dominated. We had a chance to score but if we had taken it then the performance still wouldn't have been sufficient.
"It was a big effort after playing on Wednesday and some teams have a day longer to recover but that is not enough to explain the display as we needed to respond."
With Iker Casillas injured, Mourinho once again put his confidence in Diego Lopez in goal rather than youth product Antonio Adan while Raphael Varane also kept his place after an inspirational performance against Barca.
It was a baptism of fire for Granada coach Lucas Alcaraz who only had a few training sessions with the team after being appointed this week with the side only a place above the relegation zone.
He decided against making sweeping changes but did play new signing Nolito from Benfica on the left wing, with Dani Benitez injured, while Diego Buonanotte, who moved from Malaga, waited his chance on the bench.
Madrid started with plenty of the ball but they were sluggish in their passing and with Granada defending in numbers they were able to close them down without any alarms.
The home side set out their stall to allow Madrid to keep possession in the middle of the pitch while Ronaldo and Angel Di Maria struggled to make any inroads down the wings and they lacked the in-form Mesut Ozil through suspension.
Inigo Lopez headed over for Granada from a corner after 13 minutes and they looked dangerous on several breaks but they lacked a quality final ball.
Eventually Carlos Aranda sent over a telling cross with the Madrid defence stretched after 20 minutes and Alvaro Arbeloa arrived just before Nolito at the far post to knock it behind.
From the resulting corner Granada took the lead as Nolito's cross was flicked into his own net by Ronaldo jumping at the near post.
Madrid offered little in response with shots from distance from Ronaldo and Xabi Alonso.
After the break a 25-yard strike from Ronaldo forced a good save from Tono Rodriguez and they gradually raised the pace of their game in the final half hour.
Substitute Karim Benzema had a glaring miss from a few yards out in the final minutes.
Earlier bottom side Deportivo La Coruna's plight got worse as they lost 3-1 away to Getafe despite going ahead through a Luis Pizzi penalty after eleven minutes and having a man extra with the dismissal of keeper Miguel Moya.
Getafe responded with a penalty of their own through Diego Costa and scored further goals from Alvaro Vazquez and Adrian Colunga while Depor's Abel Aguilar was also sent off in the second half.
Osasuna moved out of the relegation zone with a 1-0 win over Celta Vigo and Espanyol continued their improvement under coach Javier Aguirre with a 3-2 victory over Levante.