Knehr was recalled by the Padres on Friday.
Knehr has spent most of the season with Triple-A El Paso, where he's struggled to a 7.84 ERA in 10 starts and two relief appearances. In his lone appearance at the major-league level Saturday against the Rockies, he threw 4.2 scoreless innings of relief. He was demoted the next day but is now back with the big-league squad, with Joe Musgrove hitting the COVID-19 injured list in a corresponding move.