Now with another key piece of their lineup going down, Ryan Zimmerman's return has become all the more necessary.
The Nationals (18-10) have gone 7-6 with Zimmerman sidelined because of right shoulder inflammation, batting .228 in the games he missed as opposed to .246 with him in the lineup.
Zimmerman took batting practice before a 9-3 loss to Philadelphia on Sunday that ended a four-game winning streak and said he felt good to play Tuesday.
In the sixth inning, though, Werth broke his left wrist attempting to make a sliding catch. He's expected to miss significant time, just as manager Davey Johnson was ready to have Werth, Zimmerman and former Pirate Adam LaRoche in the lineup together again.
LaRoche, who has a team-best 17 RBIs and has missed the last four games with a bruised right oblique, also hopes to play Tuesday.
Zimmerman has gone 1 for 13 in his last four against the Pirates (12-16), who fell 5-0 to Cincinnati on Sunday and scored four runs while dropping two of three in the series.
A.J. Burnett (1-2, 8.04 ERA) will attempt to shut down the Nationals, though he's coming off one of the worst outings of his career.
Burnett allowed 12 runs and 12 hits in 2 2-3 innings of a 12-3 loss to St. Louis on Wednesday, with his ERA ballooning from the 1.38 mark he entered with.
The right-hander hasn't faced Washington since June 27, 2006, when he threw a six-hitter in a 6-0 win while pitching for Toronto. Burnett is 3-0 with a 1.98 ERA in his last five starts against the Nationals.
He'll be opposed by Edwin Jackson (1-1, 3.69), who allowed four runs in six innings and didn't get a decision in a 5-4 win over Arizona on Wednesday.
The right-hander has gone 4-0 with a 3.13 ERA in five starts against Pittsburgh.
It's official: Washington has fallen in love with rookie Bryce Harper. And why not? The kid's been with the Nationals for only eight games, but he already has caught the District's attention.
The well-publicized 19-year-old former No. 1 overall draft pick helped with a game-winning rally last week and already bats third in the lineup. In a nationally televised loss to the Phillies on Sunday night, he paid back Cole Hamels for hitting him with a pitch by stealing home. Later, Harper's hustle turned a bloop single into a double.
The Nationals Park crowd already cheers his every move.
"He's fun to watch," Nationals manager Davey Johnson said.
And Washington truly needs Harper's help now. He's batting .308 through those first eight games, and Johnson will likely move Harper to right field (from left) because Jayson Werth is out for up to 12 weeks after breaking his left wrist Sunday. Werth was scheduled to undergo surgery Monday.
This is not related to the previous wrist injury that affected Werth for up to two years earlier in his career and forced him to miss the entire 2006 season.
Johnson said he'll probably use Xavier Nady, Roger Bernadina, Chad Tracy and even Steve Lombardozzi in left field. Starting left fielder Michael Morse (lat injury) has been out the whole season and hopes to return in about a month.
"I like right field," Harper said. "I like center. I can play left also. I don't care where I play as long as I'm helping the ballclub."
Rick Ankiel is back in center after injuries held him out until April 14. When Morse and Werth come back, the Nationals should have a solid outfield.
But questions remain when and if that will happen this year. There's a good chance that it might not take place until August or later.
Werth's loss is going to hurt the Nationals, but they have to keep moving forward. They are 18-10 with a half-game lead over the Braves in the National League East going into Monday's games and have been one of the biggest surprises of 2012.
Now, they'll be asking a teenager to play like a veteran on a daily basis thanks to all of those injuries.
In addition to Werth and Morse, third baseman Ryan Zimmerman is on the disabled list, and first baseman Adam LaRoche missed the Phillies series. Zimmerman (shoulder inflammation) and LaRoche (oblique problems) could both be ready when the Nationals take the field again Tuesday in Pittsburgh.
If they aren't, that means the Nationals would be without almost half of their original lineup: Nos. 3 (Zimmerman), 4 (Morse), 5 (LaRoche) and 6 (Werth).
This is where Harper could really add to his reputation.
There's no question that he likes the spotlight. Some young players shy away from it. Harper is drawn to it, and he plays hard. The crowds in Washington have picked up on that. Harper, in turn, is proud of the way he plays and said that won't change.
"I just try to go out there and bust my butt -- and try to make something happen," Harper said.
The Nationals have gently talked to him about being careful about the way he does it. Tone it down a bit, they've said. In the minors, he blew a kiss at a pitcher after hitting a home run. Actions speak louder than words is the message Washington gave its young star.
Hamels admitted later that he did drill Harper on purpose when he hit him Sunday. But Harper didn't say a thing. He just went to first and advanced to third on a Werth single.
After that, Harper simply stole home when Hamels tried a pickoff move to first. The rookie evened the score -- and he did it on national television.
The fans went nuts. The manager liked it, too.
"He's going to battle you," Johnson said. "He had a heck of a ballgame."
--GM Mike Rizzo went ballistic after LHP Cole Hamels declared that he did hit LF Bryce Harper on purpose in the first inning Sunday night. Hamels said he's old school, and that's why he did it. Harper evened the score by getting to third on a single and then stealing home in front of a national TV audience. Folks, this is now officially a rivalry.
--RF Jayson Werth will be out up to 12 weeks after breaking his wrist in Sunday's game. He underwent surgery Monday. This injury is different from another wrist problem he had earlier in his career that bothered him for up to two years.
--LF Bryce Harper is hitting .308 after his first eight games, and manager Davey Johnson will likely move him to right field while Jayson Werth is out. Johnson plans on using a committee for left field -- Xavier Nady, Chad Tracy, Steve Lombardozzi amd Roger Bernadina -- until starter Michael Morse returns or Werth comes back. For now, though, right field belongs to Harper.
--RHP Jordan Zimmermann said he didn't hit LHP Cole Hamels on purpose when the pitcher tried to bunt a few innings after hitting Nationals OF Bryce Harper. Zimmermann said a fastball got away from him and hit the lefty in the knee while Hamels tried to bunt.
--3B Ryan Zimmerman and 1B Adam LaRoche both could return for the start of the Pirates series on Tuesday. Zimmerman has been on the disabled list with shoulder inflammation while LaRoche missed the Phillies series with oblique discomfort. LaRoche is the one who might not be ready, but he's improving daily.
BY THE NUMBERS: 12 -- Weeks RF Jayson Werth could be out after surgery to repair his broken left wrist.
QUOTE TO NOTE: "Players take care of themselves. I've never seen a more classless, gutless chicken (bleep) act in my 30 years of baseball. Cole Hamels says he's old school. He's the polar opposite of old school. He's fake tough. He thinks he's going to intimidate us after hitting our 19-year-old rookie who's eight games into the big leagues? He doesn't know who he's dealing with." -- GM Mike Rizzo's comments to The Washington Post after hearing Phillies LHP Cole Hamels admit he hit LF Bryce Harper on purpose.