MIAMI (AP) The game was scoreless until the seventh inning, and runs then came so quickly for the Washington Nationals that Bryce Harper lost count. And he drove in most of them.
Harper hit a grand slam, one of four home runs in a seven-run seventh for the Nationals, who beat the Miami Marlins 7-0 Tuesday.
Four homers in an inning was a Nationals record, and a record for Marlins pitchers.
''Everybody got together and started rolling,'' Harper said. ''Scoring those seven runs or whatever we did in the seventh - I don't know how many we had - yeah, seven - brought a little calm over the dugout and let us breathe a little bit.''
Stephen Strasburg (3-0) struck out 10 while pitching three-hit ball for eight innings. He was locked in a pitching duel against Adam Conley until Jayson Werth hit his 200th career homer with one out in the seventh.
Wilson Ramos homered on the next pitch, and after Washington loaded the bases, Harper hit his seventh homer off left-hander Chris Narveson.
''I was trying to go deep,'' Harper said. ''I got a good pitch to drive and did my job.''
Ryan Zimmerman followed with a solo homer, his first.
Harper has homered in five of the past six games, and has 20 RBIs.
''What he's doing is pretty special,'' Werth said. ''He has really coming into his own. He's one of the best players in the game, and he's got good guys around him too. That helps.''
The grand slam was the second of Harper's career, and his second in five days. Strasburg happened to be on third base for both.
''It was weird being on third again for another Harper grand slam,'' Strasburg said. ''I guess it's all on me - I've just got to get to third.''
The dimensions at Marlins Park were shortened before the season, but only Zimmerman's home run benefited from the cozier confines. Ramos' homer bounced off the top of the fence.
Washington's Daniel Murphy, who came into the game leading the majors in batting, went 2 for 4 to hike his average to .422. Strasburg had two singles to raise his career average to .149.
''Everybody is swinging the bat well,'' Harper said. ''Even Strasburg.''
The right-hander also lowered his ERA to 1.25. Strasburg gave up an extra-base hit for the first time this year when Stanton doubled with one out in the fourth, but he advanced no farther.
Nationals starters improved to 8-2 with an ERA of 1.98. Shawn Kelley completed the four-hitter for Washington's second shutout.
''If you didn't watch the game, you think it's a horrible game,'' Marlins manager Don Mattingly said. ''It was really a well-pitched game, other than some pitches in the seventh.''
Conley (0-1) extended his scoreless streak to 12 innings before he tired in the seventh. He gave up four runs in 6 2/3 innings.
''That young man was throwing well, big time,'' Nationals manager Dusty Baker said. ''The next thing you know, we had seven runs. That just shows what we're capable of doing. We should never be out of a game.''
First base umpire Jerry Layne left the game in the third inning after hurting his knee dodging a line drive hit by Murphy.
BATTING CHAMP BLING
Marlins 2B Dee Gordon received a 4-inch-wide jeweled medallion from owner Jeffrey Loria for winning the NL batting title last year. Loria presented the gift before batting practice to a surprised Gordon, who rushed onto the field to show it to his teammates.
The weather was clear and 78 degrees at first pitch, but Marlins officials reluctantly decided several hours before the game to close the retractable roof. There was a slight chance of rain in the forecast, and team president David Samson feared a surprise shower, mindful of an embarrassing rain delay on opening day 2015.
''I'm scarred,'' Samson said.
The roof has been open only once this season.
Marlins LHP Wei-Yin Chen (0-0, 5.56) is scheduled to start Wednesday against RHP Joe Ross (2-0, 0.60), who went seven innings to beat Miami on April 10.