New York Giants defensive end Michael Strahan missed practice Friday with a sore back and was listed as questionable for Sunday night's game at San Diego. Strahan, who also missed some practice time last week with back spasms before recording five tackles and a sack against the New Orleans Saints on Monday night, did not appear too worried about his latest problem. ``I'm fine,'' Strahan said. ``If I don't play on Sunday, then be concerned.''