Atlanta placed Lopez (knee) on the 15-day injured list Sunday.
Atlanta is labeling Lopez's injury as left knee inflammation, though Mark Bowman of MLB.com relays that the club is still awaiting the results of the right-hander's MRI before providing a timeline for his return. Right-hander JR Ritchie was recalled from Triple-A Gwinnett in a corresponding move and will step in as Atlanta's new fifth starter beginning with Sunday's game against the Nationals. Since moving back into the rotation in late June after a two-month stint in the bullpen, Lopez went 1-2 with a 3.86 ERA, 1.29 WHIP and 27:8 K:BB in 28 innings over six starts.