Foster was added to the White Sox's roster as the 27th man ahead of the second game of Wednesday's doubleheader against Texas.
Foster will also serve as the opening pitcher for the White Sox, as they plan on relying on their bullpen to get them through Wednesday's nightcap. The 29-year-old righty threw a scoreless inning out of the bullpen during his season debut Aug. 16, and he owns a 2.40 ERA through 15 innings at Triple-A Charlotte.