PHILADELPHIA -- Daniel Murphy's hot hitting again lifted the Washington Nationals on Monday night, allowing them to overcome not only an injury to reigning National League MVP Bryce Harper but yet another shaky outing by Jonathan Papelbon against his former team.

Murphy, the major leagues leading hitter with a .396 average, contributed a go-ahead two-run single in the eighth inning, as the Nationals beat the Philadelphia Phillies 4-3.

Murphy's hit and Papelbon's save came after Harper left the game with a sore right knee after getting by a pitch in the seventh. Harper said his knee was still sore and he will be re-evaulated Tuesday.

"It was sore, pretty numb," Harper said. "It didn't feel that great. I think sliding back into first on a double play wouldn't have helped us at all.

After Harper's injury the victory was not secure, until Papelbon wriggled out of trouble in the ninth against the team who traded him last July.

"Last time we came in here, Pap had an unfortunate outing, and we were like, it couldn't happen again," Washington manager Dusty Baker said, referring to a blown save by Papelbon in an April series against the Phillies.

Papelbon also blew two saves against Philadelphia last season.

"He may bend," Baker said, "But he doesn't break."

Murphy, signed as a free agent in January by Washington after seven years with the New York Mets, has proven to be no less resilient. He snapped a 2-2 tie with his hit off Philadelphia reliever Hector Neris (1-2), capping a three-run inning for the Nats.

"Fortunately I got a pretty good pitch to hit and found some outfield grass," Murphy said.

Murphy was 3-for-4 and also hit a solo homer off Philadelphia starter Jeremy Hellickson in the fourth inning. He has hit safely in nine straight games, has a franchise-record 45 hits in May.

"He's carrying our team," said Harper, who left the game in the bottom of the seventh, after suffering a bruised right knee when he was struck by a Hellickson pitch in the top of the inning. "It's fun to watch."

In the eyes of Nats pitcher Tanner Roark, Murphy's success is the result of preparation.

"He studies every pitcher that he faces, and it's pretty impressive," said Roark, who evened his record at 4-4 by allowing two runs and four hits in seven innings. "He loves baseball. He works hard. He wants to be the best."

"Right now he's not thinking about hitting .400," Baker said. "He's not thinking about anything other than the simplest from each at-bat, each inning at a time."

Murphy said he's just part of a larger whole.

"Traffic on the basepaths helps," he said. "High-leverage situations for the pitcher always, I think, favor the hitter. That last at-bat there was a lot of traffic out there. I was just the beneficiary of that tonight.

After Roark finished, Felipe Rivero pitched a scoreless eighth, and Papelbon entered in the ninth.

He immediately allowed a run when Maikel Franco and Ryan Howard doubled, but struck out pinch hitter Tommy Joseph and Cesar Hernandez. Tyler Goeddel lined out to Murphy for the final out and Papelbon secured his 14th save.

Freddy Galvis homered for Philadelphia, which dropped its fourth straight game and lost for the seventh time in eight games.

Galvis homered in the sixth, giving the Phillies a 2-1 lead, and Hellickson needed just 79 pitches (53 strikes) to negotiate seven innings.

Manager Pete Mackanin nonetheless inserted Neris to start the eighth. He issued a one-out walk to Danny Espinosa, a two-out walk to Ben Revere.

Jayson Werth, doubled into the left-field corner to chase home the tying run.

Chris Heisey, Harper's replacement, then walked to load the bases, and Murphy lined a 2-0 pitch from Neris into right field, making it 4-2.

Hellickson was later asked about being pulled with such a low pitch count.

"Obviously I would have liked to have stayed in," he said. "I thought it was my game to win or lose, but Hector's probably been the best eighth-inning man in the game."

Mackanin said much the same thing of Neris, who had fashioned a 1.29 ERA over his first 26 appearances.

"We've had a good combination of Neris and (closer Jeanmar) Gomez," he said, "So we thought it would be a good idea."

"I'm disappointed," Neris said. "I know I'm better than that. I'll try to forget today and get ready for tomorrow. A bad day for me."

The Phillies scored a run without a hit in the second and took a 1-0 lead on Hellickson's safety squeeze bunt.

Murphy knotted tied it by depositing Hellickson's 0-1 fastball into the right-field seats with two outs in the fourth, his eighth homer of the season.

NOTES: Phillies 1B Ryan Howard, a left-handed hitter, was back in the lineup against Washington RHP Tanner Roark, but Philadelphia manager Pete Mackanin reiterated before the game that his plan going forward is to use rookie 1B Tommy Joseph against righties on occasion. Joseph started against Chicago Cubs RHP John Lackey on Sunday. "Howie's still in the picture," Mackanin said. "He's not being benched. I'm just going to give a little more playing time to Joseph." The 36-year-old Howard, in the final year of a five-year, $125 million contract with a team option for 2017, went 1-for-4 but has just seven hits in his last 70 at-bats, leaving his average at .157.