The Nationals fear they may also be without catcher Jesus Flores for several days because of a strained right hamstring, and they plan to recall catcher Jhonatan Solano from Triple-A Syracuse on Tuesday.
Tracy was hurt Saturday against Atlanta, and he's scheduled to undergo an MRI Tuesday to determine the severity of the injury. He was 6 for 18 (.333) as a pinch hitter and batting .265 overall.
The Nationals selected the contract of outfielder Corey Brown from Syracuse, and he joined them for the start of a series at Miami. He pinch hit in the ninth inning and flied out to end the Nationals' 5-3 loss.
After the game, first baseman Tyler Moore was optioned to Syracuse to make room on the roster for Solano. Moore, a top prospect, went 3 for 19 with the Nationals, and they believe he needs to play regularly.
"We think highly of him, and he has got a great future here," manager Davey Johnson said.
Outfielder Jayson Werth, recovering from a broken left wrist, was transferred to the 60-day disabled list.
Solano, who has never played in the majors, provides added depth at catcher with uncertainty about Flores' injury. Flores was hurt Sunday at Atlanta and said he felt better Monday.
The Nationals are thin at the position after starting catcher Wilson Ramos blew out his right knee two weeks ago. He could be out for the season.
Brown, whose only previous major league experience was three games with the Nationals last year, could provide some pop off the bench. He hit .297 with 12 home runs and 30 RBIs in 48 games this season for Syracuse, with homers in his final five games there.