Washington ace Max Scherzer received a stem cell shot to treat his strained back and hopes to make his next scheduled start Tuesday against Atlanta.
Scherzer returned from the injured list Thursday and in his first start since July 6 allowed three runs and four hits over five innings during an 8-7 loss to Colorado. He had been sidelined by inflammation under his right shoulder.
An MRI on Friday revealed the mid-back strain. Scherzer will not throw for two days.
"He has a strain of his rhomboid," Nationals manager Dave Martinez said. "He's going to get shut down for two days then we'll see how he feels from there. Right now, he wants to make his next start."
A three-time Cy Young Award winner, Scherzwer was 7-0 with a 0.87 ERA in his previous seven starts before Thursday.
"I'm not happy," Scherzer said. "But on the other hand, we're talking minor strain."
Scherzer initially began to experience back problems after his start in Detroit June 30.