"I don't feel the injury in there at all [while throwing]. That's very positive," Mattheus said. "There was still a little soreness in there when I lifted for the first time."
Bill Ladson is a reporter for MLB.com and writes an MLBlog, All Nats All the Time. He also could be found on Twitter @WashingNats. This story was not subject to the approval of Major League Baseball or its clubs.