Left fielder Chris Duncan's availability for the remainder of the season is in question after the Cardinals' lefthanded slugger on Saturday aggravated what the club described as a sports hernia. Manager Tony La Russa ruled out Duncan for the final four games of a three-city trip that takes the Cardinals to Chicago for today's make-up against the Chicago Cubs and to Cincinnati for a three-game series against the Reds. Duncan will return to St. Louis for further examination and possible surgery. He pinch-hit Sunday in the ninth inning against Arizona and looked to be in discomfort as he struck out. Cardinals head trainer Barry Weinberg said, "There's no question he will require surgery at some point. The question is when." Duncan had been bothered by what La Russa had euphemistically described as a "lower half" injury for much of the past six weeks. Until Sunday, Duncan had requested that the club withhold information about his condition. Only recently had Duncan confirmed that he was dealing with symptoms akin to a lower abdominal pull. "He may be out for the year. I don't know," La Russa said before Sunday's game