It will be the first game action Ryu has seen since March 17, 2015, in the Cactus League, when the left-hander underwent surgery on the labrum in his left shoulder. He was also delayed for several days by a groin strain in April.
McCarthy threw off the mound at Dodgers Stadium on Saturday in a simulated inning with Charlie Culberson in the batter's box. The right-hander threw his full pitch mix and is expected to throw a simulated game before starting his rehab assignment.
"Obviously, the intent wasn't game-like, as far as Charlie's adrenaline, but I think he was putting forth at-bats," Dodgers manager Dave Roberts said of McCarthy's level of competition. "We just wanted a guy to be in there, a Major League hitter. He was putting some good swings, but there were also some swings and misses, so that was good to see from McCarthy's standpoint."
Pitchers on rehab assignments may stay with their assigned Minor League team for up to 30 days. Roberts has said the two pitchers could potentially return with a week of each other.
As far as who Ryu and McCarthy will replace in the rotation, rookie right-hander Ross Stripling would be the first candidate, given that he is on an innings limit due to 2014 Tommy John surgery.
The next likely candidate is veteran lefty Alex Wood, who could stay with the Major League team in the bullpen, a role he's occupied in the past with the Atlanta Braves.
Jack Baer is a reporter for MLB.com based in Los Angeles. This story was not subject to the approval of Major League Baseball or its clubs.