For the second time in three seasons, New York Giants starting cornerback William Peterson has a potentially season-ending back injury. Peterson, listed as doubtful for Sunday's game against St. Louis, said Thursday the injury could force him to miss the game and possibly the rest of the season. Peterson said the team's medical staff diagnosed a fracture of his lower back after he had an MRI exam last week. He experienced pain while playing against the San Diego Chargers on Sunday night, and said further tests this week showed the injury to be more serious. "I was told it was something I could play with that would just cause me pain, but it wouldn't cause any other damage to the back," he said. "But after the game, on Monday I was told it was more serious in nature. Right now it doesn't look good for this weekend and it doesn't look good for this season."