MADRID - Barcelona pulled six points clear of Atletico Madrid at the top of La Liga when Lionel Messi netted his seventh double of the campaign and set up Alex Song to open his account for the club in a 3-1 success at home to Real Zaragoza on Saturday.World Player of the Year Messi took his league tally for the season to 17 with a pair of beautifully executed finishes as unbeaten Barca moved on to 34 points from 12 matches.Atletico have 28 points ahead of their game at Granada on Sunday, while third-placed Real Madrid closed to within two of their city rivals when they crushed visiting Athletic Bilbao 5-1 in Saturday’s late kickoff.Real have now put 19 goals past Bilbao in their last four league meetings at the Bernabeu and the big surprise of the night was that Cristiano Ronaldo failed to add to his 12 La Liga goals this term.Messi opened the scoring in the 16th minute at the Nou Camp when he picked up Jordi Alba’s pass and clipped the ball into the bottom corner.Cameroon midfielder Song thumped a Messi pullback through a crowd of players into the net to restore Barca’s lead in the 28th minute and Messi curled in his second to kill off the game on the hour.It was his 78th goal of 2012 for club and country - 66 for Barca and 12 for Argentina - and he is closing in on the record for a calendar year of 85 set by German Gerd Mueller in 1972.Agencies