Pirates general manager Ben Cherington said Sunday that Horwitz (hamstring) will remain sidelined for "weeks, not days," and the first baseman isn't expected to return from the 10-day injured list until after the All-Star break, Colin Beazley of the Pittsburgh Post-Gazette reports.
Pittsburgh placed Horwitz on the shelf Thursday, and Cherington's comments imply that the 28-year-old is dealing with more than a mild strain of his left hamstring. Ryan O'Hearn will make a fourth consecutive start at first base Sunday and should serve as the primary option at the position until at least mid-July. Before getting hurt, Horwitz had settled in as the Pirates' leadoff hitter and had slashed .280/.386/.455 with a 40:40 BB:K, 10 home runs, 33 RBI and 36 runs on the season.