King exited Friday's game against Baltimore due to an elbow injury, Pete Caldera of The Bergen Record reports.
King was lifted suddenly in the eighth frame after completing an inning of work without allowing a baserunner. There's no official diagnosis, though any arm injury for a pitcher raises significant concern. King has been a key part of the Yankees' bullpen this season, as he's maintained a 2.29 ERA with a 66:16 K:BB across 51 innings.