MIAMI -- Nationals right fielder left Tuesday's game against the Marlins before the bottom of the second inning with soreness in his right elbow.
He was replaced by Alex Escobar.
"I just tried to make a throw and there was some swelling right away, so I don't know what's going on there," Guillen said. "I went to the field and tried to make a throw and there was just too much swelling right away."
Guillen will get an MRI on the elbow tomorrow and get a better indication as to the extent of the injury.
"We'll take an MRI wednesday and see what's going on," Guillen said.
Last season, Guillen suffered from tendinitis in his right elbow, among many other ailments, including a right wrist contusion, a pulled rib cage muscle and a bruised left wrist.
Kevin Fiorenzo is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.