Pirlo's majestic curling effort was the difference at the Ennio Tardini.
It was a match that the visitors dominated but they were only able to find the back of the net once thanks to mixture of great goaltending from Antonio Mirante and some sub-par finishing from the Rossoneri.
Still it was three vital points and the Diavoli had Andrea Pirlo to thank as his wonderful curling effort from 30-plus yards was the difference tonight.
The visitors wasted no time in showing their attacking intent as Gennaro Gattuso slipped a neat pass into the path of Zlatan Ibrahimovic, who fired his shot wide of the far post.
Former Milan man Hernan Crespo then wasted a glorious opportunity when his awkward close range header failed to beat Christian Abiatti after Alessandro Nesta did just enough to bother the Argentine striker.
It was a scrappy affair at times in the first half and the match was in danger of turning into a real slugfest until Andrea Pirlo came to the rescue with a wonderful individual effort in the 25th minute.
The Italian international picked up a loose ball in midfield and curled in a wonderful shot from 30-plus yards out that nestled into the top corner. It was sublime technique from the Milan midfielder who was mobbed by his team-mates after the wonder-strike.
The Diavoli then threatened to double their advantage when Ronaldinho's lovely weighted ball found Ibrahimovic in the clear but Mirante did ever so well to rush off his line and make a brave block.
Mirante once again kept his side in the match when he made a miraculous triple save to deny Ibrahimovic. The Swede muscled Massimo Paci off the ball and was one-on-one with the Parma keeper but could not steer his shot past him and Mirante stood tall for the rebound before kicking out the striker's third attempt.
Parma were extremely lucky only to be a goal down heading into the interval.
Both teams took some time to get going in the second half with chances at a premium although Ronaldinho showed off some of his tricks and flicks to win a free kick that he subsequently sent wide of the target.
The Diavoli had another chance to double their advantage after Ibrahimovic spotted a streaking Robinho on the right hand side but the Brazilian wasn't able to hit the target from 15 yards out.
Mirante come to the forefront again just after the hour mark when he had to be sharp to tip Ronaldinho's rasping shot over the bar.
Milan almost paid for their profligacy in the 78th minute though when Blerim Dzemaili unleashed a low drive that Abiatti pushed around the post. The Milan 'keeper was then called into action moments later when he took the ball of the shoe-laces of Crespo.
Parma were unable to create any chances after that and Milan return home with all three points and top spot in the Serie A standings before the rest of the league fixtures tomorrow.
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