Getafe upset Real Madrid 1-0 at the Bernabeu to blow open the Spanish Primera Liga title race on Sunday as Barcelona closed to within two points of the leaders after thumping Levante 5-1.
Michael Laudrup's side kept their heads when Arjen Robben's goal was ruled out midway through the second half and, while the home players disputed the decision, broke down the pitch for Nigeria striker Ikechukwu Uche to score at the other end.
The defeat brought to an end Real's perfect home record in the league this season and ended an unbeaten run there that stretched back to February 2007. It was also their fourth defeat in five games in all competitions.
"Three consecutive defeats is something to be worried about," Real midfielder Guti told Canal Plus television.
Second-placed Barcelona had ensured maximum pressure was applied with a 5-1 hammering of the league's bottom club at the Nou Camp.
Cameroon striker Samuel Eto'o netted a hat-trick, while Argentina's Lionel Messi scored one and set up two.
Levante had caused murmurs of unrest when they cancelled out Xavi's opener from the penalty spot just before the break but offered little more as Barca upped the tempo in the second half.
Earlier, Villarreal came from behind to beat Athletic Bilbao 2-1 away to strengthen their hold on third place with 46 points, eight behind Barca.
Bilbao, who had only lost twice at Sam Mames in the league, took an early lead but second-half goals from Mexico striker Guillermo Franco and Spain full back Joan Capdevila sealed the points for Manuel Pellegrini's side.
Stuttering Atletico Madrid clung to fourth with 41 points despite losing 3-1 at Osasuna and are now just two ahead of a resurgent Sevilla, who cracked five past Real Zaragoza on Saturday.
Espanyol slipped to their sixth defeat in seven games when they went down 2-0 at Deportivo Coruna and are level on 39 points with Sevilla in sixth.
PLAYERS CELEBRATING
Getafe showed the confidence that has helped them to the King's Cup semi-finals and the last 16 of the UEFA Cup in an evenly-contested game with few chances.
The turning point came when Raul was flagged as offside before Robben scored and Getafe reacted quickly while some Real players celebrated and others argued with the referee.
Barca looked to have gained the perfect start at the Nou Camp when Spain midfielder Xavi arrived late in the box to bury a loose ball in the back of the net after 14 minutes.
However, the expected flood of goals did not come straight away and it was the visitors who grew in confidence.
Midfielder Juanma's shot was pushed onto a post by Victor Valdes, and in the 41st minute Italy full back Gianluca Zambrotta's handball in the area earned Levante a penalty, which Riga duly converted.
Messi picked up Xavi's backheel and fired in from the edge of the area to restore Barca's lead a minute before halftime and he turned provider for Eto'o just after the restart with a defence-splitting pass.
Messi squared for Eto'o to make it 4-1 after a great pass from Yaya Toure in the 62nd and substitute Bojan Krkic crossed for Eto'o to complete his hat-trick three minutes from time.