Beimel, 32, sustained the injury while making a diving play on a ball off the bat of Braves second baseman Kelly Johnson in the eighth inning of Monday's game. After the out was made, the game was delayed by rain, which pleased Beimel, because he couldn't lift his left leg.
It marks the first time Beimel was placed on the DL during his eight-year career.
"I thought maybe it was a charley horse or something like that," Beimel said. "I kind of stood there hoping that it would go away, and I said, 'How in the heck am I going to do this and throw this next pitch?' And then they delayed the game. That's what I get for trying to show off."
The Nationals don't know how long Beimel will be out of action. The next few days will give the team an idea. The good news is, Beimel was able to lift his left leg on Tuesday.
Beimel was clearly Washington's best relief pitcher over the first two weeks of the season. In eight appearances, Beimel has a 1.23 ERA. He was considered the Nationals' eighth-inning man.
With Beimel gone, right-hander Garrett Mock will probably pitch in the eighth inning as the primary setup man, but manager Manny Acta didn't rule out mixing and matching with hurlers such as Jason Bergmann and Kip Wells.
Since becoming manager of the Nationals, Acta has seen his players get hit by the injury bug in a big way, and he wonders if the team is jinxed. The club currently has seven players on the disabled list.
"I don't believe in negative stuff, but I was wondering if someone buried that red cross jersey here before they built Nationals Park, because it's kind of weird," Acta said.
But despite the "jinx," some injured players are on the mend.
Shortstop Cristian Guzman, who is on the DL because of a left hamstring strain, will go to Viera, Fla., to play in extended spring games. He is expected to be activated from the disabled list on April 29.
Infielder/outfielder Willie Harris, who hasn't played in a game since April 12 because of a left oblique strain, will start a rehab assignment with Syracuse on Wednesday. He will be activated from the disabled list next Tuesday.
Bill Ladson is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.