Morgan will fly to Baltimore on Friday to see a hand specialist and get reevaluated.
Morgan hurt the hand sliding headfirst into third base on a stolen-base attempt in the first inning against the Cubs. Morgan left the game after scoring on a double by Cristian Guzman and was replaced by Willie Harris, who will now be the everyday center fielder.
"I'm happy for the opportunity to play, but not happy to see my teammate get hurt," Harris said. "Nyjer was having one hell of a season. He was our sparkplug. He came over here and we started to play better. You hate to see anyone get hurt."
Asked if Morgan should have slid into the bag feetfirst, general manager Mike Rizzo said, "Those are instinctual things. It's very difficult to change when you get to this level of baseball."
Morgan, who was acquired from the Pirates on June 30, has contributed greatly to the Nationals' second-half turnaround. He was a force in the leadoff spot, hitting .351 with one home run, 12 RBIs and a team-leading 22 stolen bases.
"It's a stumble for us, but Willie has been out there before Nyjer got here," Rizzo said. "Willie is going to be out there again. It gives him a chance to step up and do what we have him on the team for. The other guys have to step up like we did today."
In fact, Morgan was the one who ignited the rally in the first inning against the Cubs. He led off the game by drawing a walk. Morgan then stole second and third base before scoring the first run of the game.
The Nationals have not decided on Morgan's replacement on the roster. Rizzo and interim manager Jim Riggleman plan to discuss the situation on the plane ride to St. Louis.
"We are not sure about the corresponding move, so we are going to figure that out," Rizzo said. "Riggs and I are going to talk on the plane, and we'll have a corresponding move tomorrow."
Bill Ladson is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.