Beck left Sunday's game against the Athletics after being hit in the back of the left knee by a line drive, Scott Merkin of MLB.com reports.
The ball off the bat of Oakland's Khris Davis caused enough pain that the White Sox felt it would be prudent to remove Beck. The team later announced that he is day-to-day with a bruised left hamstring. Beck doesn't normally enter in high-leverage situations but has a 3.21 ERA in 28 innings of relief this season.