Foster pitched a scoreless eighth inning in Sunday's 7-2 win over the Cardinals.
Foster, who threw 25 pitches as the opener in the second game of Saturday's doubleheader, got his first exposure to late-inning work Sunday. With the White Sox leading by five runs, it wasn't high leverage, but it could be seen as manager Rick Renteria's confidence in the 25-year-old right-hander, who has yet to allow a run in 2020.