Zimmerman, given the day off Sunday against the Mets after getting hurt on Saturday, has the same injury that he sustained during Spring Training. Jerry Hairston Jr., Alex Cora and Mike Morse could play third base for the next two weeks or so. In fact, Morse was slated to be the starting third baseman on Tuesday against the Phillies before being scratched because of the flu.
Flores played in four games for Syracuse and went 2-for-13 (.154) in four games. Flores' promotion gives the Nationals three catchers, with Ivan Rodriguez and Wilson Ramos being the others. Flores will likely come off the bench as a pinch-hitter.
Flores has not played in a big league game since 2009, primarily because of a right shoulder injury.
"It has been a long time," Flores said. "I feel happy. I feel the work I've been doing the last couple of years has worked out for me. Finally, I got the call. Now, my main thing is to stay healthy and play hard whenever the manager needs me on the field."
Zimmerman reinjured his abdominal muscle in the third inning Saturday against New York when he singled and slid headfirst into second base on the throw. Zimmerman had difficulty getting up when manager Jim Riggleman and athletic trainer Lee Kuntz came to his aid. Zimmerman said he doesn't know how he strained the muscle in the first place.
"We tried to pinpoint it, but it's kind of hard to tell," said Zimmerman, who was 10-for-28 [.357] with a homer and four RBIs before going on the DL.
Riggleman said Sunday morning that Zimmerman had problems with the muscle in the Nats' previous series against the Marlins.
Zimmerman doesn't have any problems swinging the bat or playing defense, according to general manager Mike Rizzo.
"We have the same concern level that we had during Spring Training," Rizzo said. "He has an abdominal strain that he has been playing with. He is fine doing most movements -- swinging the bat, playing defense and running the bases. When he slid on the [abdomen], that's what made it sore."
It marks the second time in Zimmerman's career that he had to miss significant time because of an injury. The last time was in 2008, when he suffered a shoulder injury.
"It's frustrating," Zimmerman said about being placed on the DL. "Nobody ever wants to do it, but the important thing is to get healthy. There is a long season ahead. You have to see how it reacts over the next five days. You have to let it rest for a week. If it feels good, you can start strengthening [the muscle] and kind of go from there."
Bill Ladson is a reporter for MLB.com and writes an MLBlog, All Nats All the time He also could be found on Twitter @WashingNats. This story was not subject to the approval of Major League Baseball or its clubs.