Sunday night, as their burgeoning rivalry with the Philadelphia Phillies reached new heights and Bryce Harper stole home, the Washington Nationals absorbed news far more dispiriting than their 9-3 loss at Nationals Park. Right fielder Jayson Werth will miss at least six weeks, and probably several months, after he broke his left wrist diving to make a catch, Manager Davey Johnson said.

After the Phillies salvaged their only victory of the series, the Nationals’ clubhouse grew quieter than at any point this season. The Nationals could not celebrate Harper’s steal of home in the first inning. They could not seethe after learning Cole Hamels admitted to plunking Harper on purpose. They could only lament the loss of Werth, the right fielder who signed a seven-year, $126 million contract in December 2010.

“We seemed to be getting a little more healthy, and boom, another one of our main guys goes down,” Johnson said. “We’ve dealt with it before. We’ll deal with it again. That was a tough blow.”

The Nationals, playing without cleanup hitter Michael Morse for at least another month, expect third baseman Ryan Zimmerman and Adam LaRoche to return from injuries Tuesday in Pittsburgh. In a typical loss, they still could have basked in their renewed health, the hustle and boldness of Harper and the 106,931 fans they drew this weekend, the second most for a Nationals Park series in April or May.

Instead, they contemplated how to replace Werth. Harper, Johnson said, will move from left field to right field. In left, Johnson will rely a combination of Roger Bernadina and Xavier Nady, with Chad Tracy and Steve Lombardozzi possibly receiving some playing time, too.

“It’s going to be tough, but we’re going to have to see what some of these other guys got,” shortstop Ian Desmond said. “I think it’s going to be a good opportunity for Bernie to showcase that he’s either a big leaguer or not.

“It’s going to be a test. Teams that go the playoffs overcome things like this. When they get their guys back, they’re even stronger.

An X-ray late Sunday night revealed Werth’s break. Monday, he will received more tests and consult with Richard Berger, the specialist at the Mayo Clinic who performed a unique surgery on his wrist in 2006.

In the sixth inning, Placido Polanco hit a two-out liner to right field. Werth charged, waited until the ball had almost reached the grass and slid, extending his left arm. As he reached for the ball, his glove stuck in the turf and his wrist bent back.

Immediately, Werth curled up into a ball. He grabbed the ball and tossed it a few feet to second baseman Danny Espinosa, all he could do. He writhed on the ground until a trainer ran to see him. He walked slowly off the field, grimacing and grabbing his wrist until he disappeared down the dugout steps.

After a disappointing first season in Washington, Werth had bounced back in the first month of his second. He entered Sunday with an .807 OPS. Saturday, he drilled a game-breaking, three-run homer against his former team, perhaps his biggest hit as a National. Now, he will have to confront a demon.

On the first day of spring training in 2005, A.J. Burnett drilled Werth with a fastball. Werth missed the first 44 games, but his wrist never healed. He had surgery and missed all the 2006 season, and he still felt pain. He thought his career could be over until a surgeon at the Mayo Clinic diagnosed the injury as a UT ligament split-tear. After a unique surgery, Werth’s career blossomed.

“You feel for him,” Tracy said. “Sometimes, you’ve got to find out what we’re made of. You lose a guy like Jayson Werth, it takes a lot out of your ball team.”

Werth’s injury hung over the game, but in the first, Harper’s staggering ability shined. With two outs, Hamels drilled Harper with a 93 mph fastball in the backside, the place you hit a batter when you are trying to hit them. Afterward, Hamels freely admitted he did it on purpose.

“I was trying to hit him,” Hamels told Philadelphia reporters. “I’m not going to deny it. That’s just — you know what, it’s something that I grew up watching. That’s what happened, so I’m just trying to continue the old baseball. . . . I’m not going to injure a guy. They’re probably not going to like me for it but I’m not going to lie and say I wasn’t trying to do it.”

Informed that Hamels had hit him on purpose, Harper laughed. “He’s a great guy, great pitcher, knows how to pitch,” Harper said. “He’s an all-star. It’s all good.”

With Harper on first, Werth lined a single to left. Harper bolted all the way from first to third, not even drawing a throw.

With Tracy at the plate, Hamels become occupied by Werth at first base. He attempted to pick off Werth, and Harper crept down the line, intently focused on the play. Before the game, third base coach Bo Porter, Werth and Harper had discussed Hamels’s deliberate move to first base and believed they could exploit it.

“We saw something,” Harper said. “I took advantage of that.”

With the count 1-2, Hamels tried another toss to first. Harper bolted, hellbent for home plate. First baseman Laynce Nix pivoted and threw home. Carlos Ruiz caught the ball at his chest and tagged Harper, too late. Harper’s hard-charging, feet-first slide beat the tag, and the Nationals took a 1-0 lead. According to the Elias Sports Bureau, he had become the first teenager to steal home since Ed Kirkpatrick in 1964.

Harper had sent one message to Hamels. Hamels came to bat for the first time in the third inning, with one out and Pete Orr on first base. Hamels squared to sacrifice bunt, and Jordan Zimmermann threw a 93-mph fastball off of Hamels’s right shin. Zimmermann insisted he did not hit Hamels on purpose.

“He was bunting, and I’m going to take an out when I can get an out,” Zimmermann said. “I was trying to go away, and I cut a fastball really, really bad and hit him in the knee.”

Hamels glared at Zimmermann. Home plate umpire Andy Fletcher walked from behind the dish and warned both benches — any more intentional plunkings, and the pitcher and his manager would be ejected.

“I didn’t realize he even gave a warning until the next inning I came out there,” Zimmermann said.

At least on Sunday, Hamels had the last laugh. In the fourth inning, Hunter Pence hit a two-run homer off of Zimmermann to give the Phillies a lead they would not relinquish. Hamels did not allow another run in eight innings, striking out eight while allowing five total hits and a walk. Harper smacked two more hits, a single and a squibber to left that he turned into a hustle double.

“He proved everything he needed to prove tonight,” Desmond said.

The Nationals assumed Hamels had hit Harper on purpose even before he copped to it. Their take: The Phillies now care enough about the Nationals to view them as a threat.

“Usually it seems the Phillies aren’t that hyped up to come play us,” Desmond said. “I think that they realize that they needed to step up a little bit, and that’s nice. It’s nice to have that feeling where, ‘Hey, they’re intense over there.’ Usually when we play them, they’re not. I think that they realized that we’ve got a good ballclub and they needed to kind of take it up a notch.”

Said Tracy: “I think those guys know we’re here.”

The Nationals took little solace. As Harper spoke to reporters, one of them told him the news on Werth. Harper had yet to hear. “Did he break his wrist?” he said, disbelieving. “Wow. That’s really bad.”