The two teams took one point each, confirming a top-two finish for table-toppers Kolkata
Spanish World Cup winners Xavi and Pedro Rodriguez put Barcelona into a two-goal lead after just 17 minutes and David Villa marked his first Clasico with a brace inside two minutes (54 min, 56) before Jeffren added a late fifth as Mourinho stomached an unforgettable first defeat in charge of Real.
For Barcelona it was a fifth successive Clasico win over their arch rivals as coach Pep Guardiola maintained his 100 per cent record in the fixture and exacted revenge over Mourinho, whose Inter Milan side defeated Barcelona in last season’s Champions League semifinals.
Real went into the game unbeaten and hoping for a first win at Camp Nou since December 2007.
However, Barcelona gave old boy Mourinho, who used to work for the Catalan club as a translator under Bobby Robson, a night to forget with an emphatic win, one of the heaviest defeats in his glittering career, that evoked memories of the 6-2 drubbing of Madrid at the Santiago Bernabeu in May 2009.
It was a huge psychological win for Barca in the title race and the omens are good with the winner of the first Clasico going on to be crowned champions in the last six seasons.
Argentine striker Gonzalo Higuain was a last-minute withdrawal for Real due to injury so French international Karim Benzema was handed a chance to shine on the biggest stage.
Guardiola said Real were the best counter-attacking team in the world but said Barcelona would attack and they were good to their word.
In the fifth minute Messi surprised everyone by curling a beautiful left-footed chip onto the post with Iker Casillas well beaten.
It was a warning that Real didn’t heed and on nine minutes the hosts took the lead through Xavi.
Andres Iniesta fed a pass into the penalty area with Marcelo failing to intercept the pass and Xavi took advantage of a fortunate piece of control to prod calmly past Casillas to the delight of the home fans.
The visitors responded with Angel di Maria forcing Victor Valdes to tip over a fierce shot but Barcelona were looking dangerous and struck again on 17 minutes through Pedro.
Villa went past Sergio Ramos by the touchline and Casillas could only fingertip his cross into the path of the inrushing Pedro who fired home.
Cristiano Ronaldo, top-scorer in the league with 14 goals, a took centre stage with his pass almost reaching Benzema only for Eric Abidal to avert the danger.
On the half hour mark Ronaldo started a melee when he pushed Barca coach Guardiola for holding the ball, earning him a yellow card, and then whistled a fine free-kick past the post of Victor Valdes.
Real brought off the ineffective Mesut Ozil at half-time with Lass Diarra replacing him but it was more of the same as Barcelona dominated.
The two teams took one point each, confirming a top-two finish for table-toppers Kolkata
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