Johnson was placed on the 10-day injured list Friday with right elbow tendinitis, Dennis Lin of The Athletic reports.
Johnson has recorded five holds with a 4.50 ERA, 1.67 WHIP and 11:4 K:BB over six innings this season, but he's now sidelined by an elbow injury. Ray Kerr was promoted from Triple-A El Paso to replace him in San Diego's bullpen.