Whitlock has been unavailable to pitch since tweaking his left knee on a wet mound in his last appearance Sunday against the Twins, Jen McCaffrey of The Athletic reports.
Whitlock underwent an MRI, which came back negative. The Red Sox do not anticipate the reliever requiring a stint on the injured list, but they would like to avoid using Whitlock for a few more days to allow for additional rest. Whitlock has collected a 3.20 ERA, nine holds and a 25:6 K:BB over 19.2 innings in a setup role for Boston this season.