The Phillies selected Keller's contract from Triple-A Lehigh Valley ahead of his scheduled appearance Saturday against the Yankees.
Keller, 32, will be making his MLB debut as a bulk reliever Saturday after posting a 2.23 ERA, 1.02 WHIP and 38:11 K:BB across 36.1 innings at Lehigh Valley. Alex McFarlane and Max Lazar were sent down to Triple-A as part of a roster shuffle, and Tanner Banks (forearm) was transferred to the 60-day IL to clear a 40-man spot for Keller.