The Rossoneri have revealed that the Brazil international will not return to match action in the 2011-12 campaign after having picked up yet another knock.AC Milan health coordinator Jean-Pierre Meersseman has confirmed that attacker Alexandre Pato will be sidelined for the remainder of the season due to a muscle injury.The Brazilian forward made his comeback after long recuperation in Tuesday\'s 3-1 Champions League quarter-final loss against Barcelona, but was forced to leave the pitch again only 14 minutes after coming off the bench.The Rossoneri immediately feared for another lengthy injury lay-off, and Meersseman has now revealed that Pato will be unavailable for the rest of the season.\"Pato\'s season is over. We are back to square one again,\" Meersseman said to La Gazzetta dello Sport.\"How can we permanently solve his muscular problems? We\'ve taken him everywhere, from Germany to the USA. Loads of doctors have examined and treated him.\"I did not get a minute of sleep all night. When I saw on TV that he felt pain again, I felt bad as well. I did not expect this to happen. Pato was declared fit again, but evidently the injury didn\'t heal.\"Pato has made only 11 Serie A appearances this term due to his ongoing injury concerns.