Magill was called up from Triple-A Albuquerque and arrived in the Los Angeles clubhouse about 2½ hours before game time Sunday.
To make room on the roster, the Dodgers placed catcher A.J. Ellis on the 15-day disabled list with a left oblique strain. The move is retroactive to May 30.
Ryu said the day before he was dealing with a sore foot and wasn't sure if he would be able to pitch. The lefty is 6-2 with a 2.89 ERA this season.
The injury-riddled Dodgers placed outfielder Matt Kemp on the disabled list last week with a strained right hamstring.