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5/27/2014 8:03 P.M. ET

Zimmerman set to take BP, field grounders

WASHINGTON -- Nationals third baseman Ryan Zimmerman will take batting practice and field ground balls Wednesday for the first time since fracturing his right thumb on April 12 against the Braves, manager Matt Williams said Tuesday.

Team doctors cleared Zimmerman to resume baseball activities on Monday after X-rays showed his fracture had sufficiently healed. He threw lightly before the Nationals' series-opening loss to the Marlins on Monday, and he also threw from around 90 feet before Tuesday night's game.

Williams said Zimmerman, who will miss his 41st straight game on Wednesday, took front-toss in the batting cage without any issue, but the team will be careful with the entire rehab process.

"All indications are that he's not going to damage his thumb any more by swinging the bat, but it could be sore," Williams said. "There's vibration that goes into it. He's been out for some time, so we worry about his back and taking too many swings all at once."

Wednesday will be Zimmerman's first time facing live pitching since he injured his thumb sliding back into the base. Williams said the third baseman will also throw from 90 feet again Wednesday, and he expects Zimmerman to make throws to second base during fielding practice.

In terms of Zimmerman's return to games, Williams said the third baseman would likely first come back in a designated-hitter role against an American League opponent before playing in the field. The manager also didn't rule out playing Zimmerman in the outfield once he officially overcomes his injury.

"There may be times where he has to do that," Williams said. "We don't know. But we're covering all the bases, at this point."

Williams said the most important aspect of Zimmerman's rehab is avoiding a relapse, both in terms of his thumb and arthritic right shoulder. Because of that, the manager said the team would have to take a patient approach, meaning there is still no timetable for Zimmerman's return.

"He's going to have to take it slow and build up to where he just can go out there and throw 40 balls across the infield and have no problem," Williams said. "You can't do it right out of the gate, though, or anybody would get sore. That's part of the process."

Nats' bullpen has been lights-out through two months

WASHINGTON -- Heading into Tuesday night's postponed contest against the Marlins, the Nationals' bullpen boasted a 2.09 ERA, which ranked first in the Major Leagues. Reliever Tyler Clippard said the group's exceptional performance so far this season has been a function of each pitcher understanding his respective role.

Right-hander Drew Storen has typically pitched the seventh inning, Clippard the eighth and closer Rafael Soriano the ninth. Meanwhile, left-hander Ross Detwiler and right-hander Craig Stammen -- who manager Matt Williams said are "vital" to the bullpen's success because of their ability to pitch multiple innings -- have taken on the middle innings.

"The bullpen is a pretty chaotic environment, in general," said Clippard, who had compiled a 1.54 ERA with 31 strikeouts in 23 1/3 innings heading into Tuesday. "So when you can kind of get a feel of knowing when you're going to get in the game and prepare properly, you have a better chance of success."

Clippard said the bullpen also has been forced to perform at a high level because of the number of close games the Nationals have played. Of the 23 games the team has played in May, 11 have been decided by two or fewer runs.

"When we're coming into the game, we can't afford to give up runs," Clippard said. "We're battling our butts off to keep our team in the game."

Worth noting

• Left-hander Gio Gonzalez (shoulder inflammation) threw on flat ground Tuesday for the fourth straight day, and second straight day from 120 feet. Williams said Gonzalez threw the ball harder on Tuesday than he did on Monday, and barring any setback, he will look to set up a bullpen session in the near future.

Daniel Popper is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.