The Phillies on Tuesday reinstated Orion Kerkering from the 15-day injured list ahead of their game in San Francisco.
Kyle Backhus was optioned to Lehigh Valley.
Kerkering, 25, had been out with a right hamstring strain suffered in spring training. He allowed one run in four innings over four rehab appearances in Triple A.
The 25-year-old right-handed reliever made 69 appearances with an 8-4 record, four saves, 19 holds and a 3.30 ERA in 60 innings pitched last season for the Phillies, his third season in the big leagues. Kerkering was a fifth-round pick of the Phillies in the 2022 MLB Draft.
Backhus, 27, had a 9.00 ERA in four relief appearances covering three innings. The 6-3, side-arming lefty was acquired in December. He had one bad outing on opening day against Texas but held batters scoreless over 2.2 innings since.