Barcelona took a huge step towards the Champions League final when a Ludovic Giuly goal earned them a 1-0 win over AC Milan in their semi-final away leg at the San Siro.

Frenchman Giuly finished sharply in the 57th minute after a superb though ball from Brazilian Ronaldinho, despite Milan having gone close to an opener three times beforehand.

Alberto Gilardino hit the post in the 14th minute and then Andriy Shevchenko had a header parried by Barca keeper Victor Valdes before Gilardino wasted a great chance in the 51st.

Barca could have come away with an even better result however, if Ronaldinho's shot across goalkeeper Dida had not struck the inside of the post and rolled back across the goal-face and out for a goal-kick.

With nine minutes remaining Milan substitute Massimo Ambrosini screwed a golden opportunity wide after a sublime pass from Kaka.

"It was a good win against a great team," Ronaldinho told Canal Plus TV in Spain. "We played a very good first half and then made use of the extra space in the second. But this tie is far from over and there are still 90 very tough minutes to come."

Milan have been clinical in their finishing throughout the competition this season but they missed the sharpness of Filippo Inzaghi in front of goal.  The Italian was sidelined due to a virus.

The result gives the Catalan club a great chance for the second-leg on April 26th as they seek to add to their solitary European Cup success.

Milan coach Carlo Ancelotti left captain Paolo Maldini and Brazilian Cafu on the bench with Dutchman Jaap Stam and Brazilian Serginho operating in the full-back roles.

The Italian side, playing in their third Champions League semi-final in four years, dominated the early exchanges in front of a passionate 76,000 capacity crowd.

Gilardino, who replaced Inzaghi in attack, struck the post from a tight angle in the 14th minute after turning sharply as he received a long throw from Serginho.

A minute later Clarence Seedorf burst down the left and whipped in a bouncing cross which Shevchenko headed powerfully goalwards but Barcelona keeper Victor Valdes made a good diving save.

Milan went close again six minutes after the restart when Shevchenko flicked the ball to Kaka inside the area and the Brazilian, who could have shot himself, fed Gilardino but the Italy forward fired wide.

Six minutes later Barcelona had the lead. Ronaldinho split the Milan defence open and Giuly, anticipating the delivery and losing his marker Kakha Kaladze with a sharp diagonal run, beat Dida with a precise left-foot finish.

It was almost 2-0 shortly after when Barca hit the post, Giuly broke on the counter-attack feeding Ronaldinho whose nonchalant shot from the edge of the area struck Dida's right-hand post.

With the Spanish side dominating midfield, Dida was forced into action in the 66th minute to keep out a smart shot from Andres Iniesta as Ancelotti's side looked in danger of letting the game slip out of control.

The Milan coach responded by bringing on Maldini for an out-of-sorts Andrea Pirlo, pushing Serginho forward into midfield and then introduced Massimo Ambrosini for Gennaro Gattuso.

It was Ambrosini who wasted Milan's next opportunity, missing the target having got behind the Barcelona defence.

If the Italian side are to keep alive their hopes of a seventh European Cup win then they will need to rediscover their killer instinct at the Nou Camp but chances may be harder to find against Frank Rijkaard's impressive side.