"We'll just get him out of here and make sure that he tries to [get over the illness]. Other than that, we are good." Williams said.
Meanwhile, third baseman Ryan Zimmerman sat his second straight game due to what Williams called minor shoulder and body tightness. The current plan is for Zimmerman to return to the lineup on Saturday against the Marlins, and Williams is not concerned, even though Zimmerman has endured shoulder surgery in the past.
"We're just being a little overcautious with him," Williams said. "I think he's fine. I wouldn't have any reason to think otherwise. He's been going through the whole thing already, all the drills, all the games, everything."
In Thursday's 7-5 loss to the Mets, Williams removed Harper after four innings because the outfielder was not feeling well.
Bill Ladson is a reporter for MLB.com and writes an MLBlog, All Nats All the time. Follow him on Twitter @WashingNats. Andrew Simon is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.