A brilliant brace from the Argentine maestro separates the sides after a heated affair at the Bernabeu sees Pepe and Pinto red carded and Mourinho sent to the stands
The drama ensued in the second half when Real Madrid were forced to play the final half an hour with 10 men after Pepe was sent off for a high challenge on Dani Alves.
Madrid’s mission worsened when they found themselves a goal down in the 77th minute when Messi expertly guided home Ibrahim Afellay’s cross to give Barcelona a 1-0 victory at the Bernabeu.
The Argentine star then produced a sensational moment of pure football when he waltzed past four Madrid players before touching the ball beyond Iker Casillas to send the travelling support into raptures.
The opening exchanges took the same route as the recent El Clasicos with neither side being able to settle early on and referee Wolfgang Stark heavily involved. Both sides looked to influence him as they attempted to gain a psychological hold on the German official.
Barcelona began to enjoy possession in their own half, as the match developed, and came close to taking the lead when David Villa darted in field. The Spaniard looked to strike the ball across Casillas, but Villa’s effort flashed past the far post.
Marcelo ventured forward as the Brazilian was determined to chase down his own knock, winning a deserved corner as a result. Madrid hastily took the kick only for Angel di Maria to waste the promising crossing position to the frustration of his team-mates.
Casillas made the game's first stop when he got down low to save from Barcelona’s Xavi. Messi had threaded a beautiful pass through to the Spanish international who took the shot on first time, firing across Madrid’s goal.
The Argentine repeated his contribution soon afterwards, this time finding Villa behind Real Madrid’s defence but the striker’s touch deserted him as the hosts saw out the danger with ease.
Clasico Mayhem | Altercation between the players from both sides at the half-time whistle
The officials became central to the tie as tempers began to rise with the match becoming increasingly tense with referee Stark looking to exert control on proceedings.
Barcelona showed what they are capable of with a magical one-touch move which ended with Villa’s flick having too much pace allowing Alvaro Arbeloa to beat Messi to the ball.
The half came to life in the final minutes when Cristiano Ronaldo crashed a long-range effort which had Valdes in trouble. His save landed at the feet of Mesut Oezil, who was spared embarrassment when the offside flag was raised after his subsequent shot was blocked.
As the players headed down the tunnel there was a ruckus between members of both teams, as an argument broke out, earning Barcelona’s second-choice goalkeeper Jose Pinto a red card.
The whistle had brought the most drama, adding fuel to the fire for when the two sides re-emerged for the second half.
The visitors began the brighter of the two in the second period with Messi finding space between the midfield and defence. He shifted the ball onto Pedro who found the Argentine with a delicate cross but Pepe recovered to nick the ball before Casillas was tested.
Barcelona took a quick free kick as they looked to get Messi away and the striker took it beyond three Madrid players before Sergio Ramos body-checked the Argentine.
The challenge earned Ramos a yellow card, which will see the defender miss the return leg. Javier Mascherano levelled the caution count soon after when he went in recklessly on Pepe.
Drama unfolded when Pepe was sent off for a high challenge showing his studs on Dani Alves, leaving the Madrid bench in wonderment of the decision.
Jose Mourinho had contested the referee’s judgment and was sent to the stands after he sarcastically praised the fourth official after Pepe’s sending off.
Barcelona looked to take the initiative with the numerical advantage and Villa produced a fine save from Casillas as the Blaugrana began their onslaught on Madrid’s goal.
Soon after, the Spanish stopper could do nothing to prevent Barcelona from taking the lead. Messi stole a march on Ramos to expertly steer home his 10th Champions League goal of the season and give Barcelona a valuable away goal.
What followed was spectacular. Messi picked the ball up 30 yards out before turning toward goal; he then took the ball past several Madrid defenders with increasing acceleration and majestically tucked the finish in the bottom corner to condemn Madrid to their first home loss in the Champions League.
Guardiola’s side greeted the final whistle with a feeling of jubilation as they will welcome the Cope del Rey champions to the Camp Nou next Tuesday with one foot firmly on the path to the final at Wembley on May 28.