A second-half brace from David Villa led Barcelona to an incredible 5-0 rout of Real Madrid in El Clasico and saw the Catalans leapfrog their fierce rivals - who lost for the first time under Jose Mourinho - at the top of the Primera Division.
Mourinho had gone unbeaten in his first 19 games in all competitions since joining Madrid in the summer, but the Portuguese was unable to avoid defeat in the biggest one of all as Pep Guardiola maintained his perfect record as Barca coach in El Clasico with a fifth straight victory over Real.
Xavi and Pedro put Barca two up within 17 minutes, while Villa made it a night to remember at a packed Camp Nou with two goals early in the second half and substitute Jeffren Suarez added a fifth right at the end.
To add insult to injury for Madrid, they finished the match with ten men after Sergio Ramos pushed Carles Puyol in the face late on.
It was some revenge for Barca - and Guardiola - after Mourinho, then coach of Inter Milan, knocked the Catalan side out of the Champions League at the semi-final stage last season here.
Mourinho handed a rare start to France striker Karim Benzema, out of favour for most of this season, after Gonzalo Higuain failed a late fitness test. Guardiola, though, was able to field his strongest XI, which of course included Lionel Messi.
And the Argentina winger, yet to score against a side coached by Mourinho, almost did so after five minutes, when he beat Madrid 'keeper Iker Casillas with an exquisite chip from a tight angle, only to see his effort rebound off the post.
But four minutes later, Barca did go ahead.
Andres Iniesta's perfectly-weighted through-ball found Xavi and the midfielder took one touch to control, albeit with some fortune, before clipping the ball past Casillas on the volley from close range.
Angel di Maria tested Victor Valdes with a stinging effort at the other end two minutes later, but Barca made it 2-0 in their very next attack.
It came after 17 minutes and was scored by Barca's number 17 - Pedro. The Spain forward was left with a simple tap-in from close range after Casillas failed to deal with Villa's low cross from the left.
That followed a long passing move from the home side and the Catalans looked good for their lead.
An unseemly brawl followed after half an hour, when Cristiano Ronaldo pushed Guardiola in the chest, with the Barca coach having refused to hand the ball to the Portugal winger on the touchline. Ronaldo was shown the yellow card and received huge jeers every time he touched the ball after that.
The former Manchester United forward came close with a free-kick later in the half and also saw a decent penalty appeal turned down after he went to ground following a challenge with Valdes. Messi was booked for simulation a minute before the interval for exaggerating a foul by Ricardo Carvalho.
Barca began the second half brightly and after Xavi and Villa missed good chances early on, the latter made it 3-0 with only 54 minutes on the clock.
The Spain striker latched onto Messi's pass and beat Casillas with a clinical finish in the area, although he looked to be marginally offside when the ball was played.
The same combination made it 4-0 three minutes later as Messi set up Villa once more and the former Valencia forward slid the ball through Casillas' legs as the 'keeper came out to narrow the angle.
The Camp Nou was rocking after that and Barca dominated right until the end. Substitute Bojan Krkic saw his fierce effort saved by Casillas and was unable to stay on his feet as he raced clear moments earlier.
But Jeffren, who replaced Pedro with three minutes left, did make it five in added time when he clipped the ball past Casillas from close range after a low cross from the right.
Madrid's misery was compounded right at the end as the visitors finished the game with ten men after Ramos hit out at Puyol and was shown the red card.