Quarterback Trent Dilfer will start for the San Francisco 49ers on Sunday against the New York Giants, though Alex Smith also will be in uniform. Coach Mike Nolan made his decision Thursday after watching two days of practice with Dilfer and Smith, who separated his right shoulder on the third play of San Francisco's 23-3 loss to Seattle on Sept. 30. Dilfer, a 14th-year pro, is 24-of-52 for 254 yards with three interceptions and one touchdown pass since then.