Underwood (illness) will report to Triple-A Indianapolis on Monday to begin a rehab assignment, Alex Stumpf of DKPittsburghSports.com reports.
Underwood has been on the COVID-19-related injured list since testing positive for the virus June 13 and may require multiple rehab appearances before the Pirates activate him. Prior to landing on the IL, the reliever turned in a 4.24 ERA and 1.29 WHIP across 17 innings out of the bullpen.