Philip Humber's scheduled minor-league rehab start for the Class AA Birmingham Barons on Wednesday was postponed by rain.

If Humber pitches in Thursday's rescheduled doubleheader, he would have four days rest before a possible start for the White Sox against the Red Sox in Boston on Tuesday night.

Humber, who is 3-4 with a 6.01 ERA, has made two minor-league starts while recovering from a right elbow flexor strain.

The Sox resume play after the All-Star break with a three-game series starting Friday in Kansas City.