WASHINGTON — Stephen Strasburg won a duel with Cole Hamels, Bryce Harper aggravated a knee, and the Washington Nationals managed to score five runs in an inning for the first time this season.
Still, it is not enough for Davey Johnson to start shaving.
Sunday’s 6-1 win kept Washington above .500 and ahead of the Philadelphia Phillies in the NL East.
Strasburg (3-5), who has pitched better than his record indicates, struck out a season-high nine and walked one in eight innings.
Philadelphia scored its only run in the eighth on Strasburg’s first big league balk. He’s allowed three earned runs in his last four starts, lowering his ERA to 2.49 in a season when his offensive support has been so lacking that the Nationals manager vowed to put away his razor until it improves.
‘‘The last two starts are probably the best we’ve seen him since we’ve been here in the big leagues,’’ Washington’s Ian Desmond said. ‘‘Obviously the punchouts and all the stuff that came before are great, but he’s starting to figure it out on another level. He’s a young guy growing up.’’
Washington set a season high for runs in an inning in the seventh, breaking open a scoreless game by putting up five against Hamels (1-8) with the help of an infield hit and a couple of errors.
The key moment was a broken-bat dribbler to third by Jhonatan Solano with the bases loaded. Michael Young charged the ball but made a low throw to home, and the ball scooted away as two runners scored. Steve Lombardozzi followed with a two-run double that chased Hamels.
‘‘A couple of weeks ago, they probably would have turned a double play on that swinging bunt by Solano somehow, someway,’’ Desmond said. ‘‘Things are starting to unfold. We’re starting to play the game better.’’
But not enough for Johnson to shave. He said the facial hair is ‘‘getting close’’ to coming off, but pitcher Gio Gonzalez lobbied otherwise, telling the manager: ‘‘It’s not shaggy enough.’’
Washington might have to play without Harper for a while after he banged his left knee three times, twice with headfirst slides in the first inning. He slid into second on an infield hit-and-error, then hit the dirt with a steal of third. He was removed for pinch runner in the seventh.
‘‘He’ll probably be down a few days,’’ Johnson said. ‘‘I don’t know if there’s fluid on the knee or what, but he was certainly gimpy.’’
Harper initially hurt the knee running into a Dodger Stadium wall on May 13. He quickly answered ‘‘no’’ when asked whether he expected to miss any playing time.
‘‘It probably won’t get better until the offseason,’’ he said. ‘‘I’ve just got to deal with the pain.’’
Johnson also announced that lefthander Ross Detwiler will miss a second start and go on the 15-day disabled list because of a strained oblique muscle. His stint on the DL will be retroactive in the hopes that he can return to the rotation Sunday.
Hamels (1-8) had his latest no-support outing, striking out six and allowing only three hits through six innings. He has lost five straight starts, has had only 20 runs of support scored all season when he’s been in the game and hasn’t pitched with a lead since April 7.