Leaders Real Madrid beat their arch-rivals and closest challengers Barcelona 1-0 at the Nou Camp to take a vice-like hold on the Primera Liga title race on Sunday.
Julio Baptista's well-taken first-half goal secured the Spanish champions only their second league victory in 24 years at Barca's ground, ended the Catalans' 100 percent home record this season, and sent them seven points clear at the top.
Real looked sharper throughout while Barcelona appeared paralysed with nerves and offered little once their visitors had edged ahead.
Bernd Schuster, after his first 'clasico' as coach, goes into the mid-season break sitting pretty with 41 points. Barca are second with 34.
Earlier, Espanyol came from behind to beat nine-man Atletico Madrid 2-1 away to climb to third on 33.
Portugal's Simao Sabrosa had given Atletico a first-half lead with a superb freekick, despite them being down to 10 men following the red card shown to their Argentine top scorer Sergio Aguero.
Raul Tamudo levelled just after the restart and with Atletico reduced to nine soon after when Mariano Pernia was dismissed, Luis Garcia raced on to Ivan de la Pena's pass to strike the winner with five minutes left.
Villarreal, who were held 1-1 at home by Recreativo Huelva, are fourth with 32, one ahead of Atletico who slipped to fifth.
Barca coach Frank Rijkaard sprung something of a surprise when he aligned Ronaldinho and Deco in his starting 11 after a week of heated speculation.
Although Barca dominated the ball early on, they were given little space to work their passes and Real had the first clear effort when Pepe headed straight at Victor Valdes from a Wesley Sneijder freekick.
Andres Iniesta sent Samuel Eto'o scampering into the area after 29 minutes but Iker Casillas was quick off his line to smother the danger and then poke the ball off the foot of Iniesta in the follow up.
Barca appeared to be upping the tempo when Iniesta streaked down the right and crossed for Ronaldinho to hit a first-time shot, but Casillas pulled off a marvellous reflex save.
Almost immediately in the 36th minute, Real took the lead on a lightning quick break when Brazilian midfielder Baptista received a cushioned return pass from Ruud van Nistelrooy to thump the ball into the far top corner.
Real did not let Barca settle, pressuring them in every corner of the pitch, and the home side were clearly rattled as the second-half minutes ticked by.
Rijkaard brought on Giovani dos Santos and Bojan Krkic in an attempt to pep up his attack to little avail, as they clearly missed the cutting edge of injured top scorer Lionel Messi.
Brazilian Ronaldinho remained a forlorn figure wide on the left and ended up being whistled near the end.
On the other hand, every time Real broke forward they looked like adding to the score with Robinho, Van Nistelrooy and their man-of-the match Baptista a constant threat.
Real showed greater bite in the tackle and they strangled the life out of their opponents and only a late flurry from Barca promised an equaliser.
Bojan tested Casillas from outside the area and Eto'o's goal-bound shot in a crowded area cannoned off Pepe with two minutes left, but in reality Barca went out with a whimper.