To make room for Callaspo on the active roster, Oakland optioned first baseman Nate Freiman to Triple-A Sacramento.
Callaspo had been on the DL since July 12 because of a strained right hamstring. He has started more than a dozen games each at first, second and third this season.
Another Athletics switch-hitter, center fielder Coco Crisp, did not start because his neck was bothering him, according to manager Bob Melvin. Craig Gentry was in center field.