The Minnesota Vikings hope to have running back Adrian Peterson, who tore two ligaments in his left knee in a game Saturday, back early in the 2012 NFL season, coach Leslie Frazier said Monday. \"I?m pretty optimistic that\'s a realistic goal,\" Frazier said in a press conference at the team\'s headquarters in Eden Prairie, Minnesota. The team\'s head athletic trainer, Eric Sugarman, said Peterson had already begun rehabilitation aimed at reducing swelling in order to prepare for surgery within a fortnight. Typically, he said, recovery time is eight to nine months and, like Frazier, he said he expected Peterson\'s work ethic to see him through the difficult rehabilitation. \"I think if anyone can get better quickly and safely in that time period, it would be Adrian Peterson,\" Sugarman said. \"We are going to hold the goal to have him ready for the first game. We do think the potential is to have him ready for the beginning portion of next season, so that is going to be our goal.\" In September, Peterson inked a seven-year contract extension worth $100 million. He was hurt when he was hit during the Vikings 33-26 victory over Washington.