According to the Boston Globe, the Red Sox may have put in the claim, but that will not be known until Monday, according to a baseball source. Acting general manager Mike Rizzo declined to comment on the situation.
The Red Sox are in need of a shortstop, as Jed Lowrie went on the disabled list on Saturday with a left wrist injury.
Guzman is having another solid season with the Nationals, hitting .315 with five home runs and 39 RBIs entering Sunday's action.
Early in the season, the Nationals were unhappy with Guzman's defense, claiming that he had problems going to his left. But interim manager Jim Riggleman considers Guzman the team's most improved player on defense since the All-Star break.
"I think Guzman has played real well the last month. Defensively, I don't remember an error he has made," Riggleman said.
Bill Ladson is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.