Morgan, who had missed the previous three games with the flu, drew a leadoff walk against the Chicago Cubs before stealing second and third. He remained in the game to score on Cristian Guzman's RBI double, but was replaced by Willie Harris before the Nationals took the field in the bottom of the first.
Nationals general manager Mike Rizzo said Morgan broke the second metacarpal bone and will fly back to Washington to visit a hand specialist. Rizzo called it a "six-week injury."
Morgan had assumed a leadership role since being acquired in trade from Pittsburgh on June 30. He also had been an offensive catalyst, hitting .351 with 24 stolen bases and 35 runs in 48 games with Washington.