Peguero is starting at shortstop and batting eighth in Saturday's game against the Giants.
Peguero was called up by the Pirates on Friday, and he'll make his major-league debut as Saturday's starting shortstop. Over 54 games at Double-A Altoona to begin the year, the 21-year-old slashed .292/.315/.469 with five home runs, 33 RBI, 28 runs and 14 steals.