Manager Manny Acta confirmed that Perez, who left his most recent start June 3 after the third inning with tendinitis in his throwing shoulder, is still hurting. The team hadn't put Perez on the disabled list in the hopes he could pitch Saturday in Seattle.
"He's not going to be able to, and the plan is we're expecting to recall somebody to take his spot," Acta said.
Twice already this week, the Nationals recalled a pitcher for a spot start. Garrett Mock made his major-league debut Sunday, losing to the San Francisco Giants. Rookie Tyler Clippard was the starter in a loss to the Giants on Monday. Each was sent to the minors immediately after his outing.
Acta was noncommittal as to which -- if either -- would be called upon to start Saturday. Acta also would not say if Perez would be placed on the disabled list, but that seems likely because the move would be retroactive to his previous start.
Perez had said that the shoulder was bothering him during prior starts.
"I just want to be 100 percent ready to go," he said. "I don't want to be pitching uncomfortably. If you're pitching with pain, it's hard to be able to stay at a level as high as you want to.
"If it's five or six more days or 10 more days, perfect," he said. "We just want to get it to 100 percent."