Jets second-year quarterback Kellen Clemens will replace Chad Pennington and make his first NFL start against the Baltimore Ravens on Sunday, according to three people familiar with the severity of Pennington's right ankle injury and the Jets' plans. The people spoke on condition of anonymity because all official injury information must come from the team. "Chad's not going to play (against the Ravens)," one person said yesterday. "It's Kellen." The injury is the latest in a star-crossed career for Pennington, who played all 16 regular-season games last season for the first time. He suffered a severely sprained or bruised right ankle -- the team still has not classified the severity of the injury -- last Sunday against the Patriots. There was no fracture, according to someone who received a preliminary evaluation of the injury, and Pennington could be ready to play next week against the Dolphins.