Manager Pat Murphy said after Thursday's game against the Giants that Hall was removed due to left pectoral discomfort, Adam McCalvy of MLB.com reports.
Murphy added that Hall is slated to undergo an MRI to determine the severity of his injury, so more information on his status may be available ahead of the Brewers' series opener against Colorado on Friday. The 27-year-old southpaw has been enjoying one of the best seasons of his career so far, posting a 2.03 ERA and 1.23 WHIP through 31 innings.