Jordany Valdespin led off the game and reached base on an error by shortstop Ian Desmond.
"I booted it. It is as simple as that," Desmond said. "[Valdespin] is quick. I make it more times than not. But what are you going to do?"
After he reached third on a single by Daniel Murphy, Valdespin scored on a wild pitch by Strasburg. Murphy then scored on a single to left by John Buck to give New York a 2-0 lead.
"[Strasburg] was missing all night, pitching behind hitters all night, threw a lot of pitches, but we had our chances," Nationals manager Davey Johnson said.
New York then added to its lead off Strasburg in the bottom of the sixth inning, when Ike Davis and Lucas Duda hit solo home runs to make it a 4-0 game.
The Nationals couldn't do anything against Harvey during the first six innings. He allowed two hits and struck out six batters in those innings.
"He threw the ball well. He is a good young pitcher. I was impressed," Johnson said. "He had a lot of things working good for him. He made a lot of quality pitches. We had our chance and we didn't capitalize on it."
Desmond said it didn't help that the Nationals haven't faced Harvey much in recent years.
"He is good. We don't have many career at-bats off him. He has electric stuff. He is an ace," Desmond said. "It kind of takes time to know who you are facing. I think we may have seen him once before. But he is on a hot streak. ... He has good stuff."
During the bottom of the sixth inning, Mets fans knew, on Friday, anyway, who won the first round of the rivalry between Harvey and Strasburg. The fans could be heard chanting, "Harvey's better!" But he ran into trouble in the seventh inning. With runners on first and second, Chad Tracy singled to left field, scoring Adam LaRoche to make it a 4-1 game.
The Nationals then had the bases loaded with no outs, but couldn't take advantage of the situation as fans chanted, "Harvey! Harvey! Harvey!" Kurt Suzuki struck out, pinch-hitter Roger Bernadina popped to Buck behind the plate and Denard Span grounded out to Murphy at second base to end the inning.
Johnson thought about using Ryan Zimmerman as a pinch-hitter in that inning, but Zimmerman couldn't play because of a left hamstring cramp.
"It's very disappointing," Johnson said. "We have been swinging the bats decently. Awful temptation to hit Zim. With his leg, I couldn't take a chance on that. But we had the right guys, we had pitches, we didn't get the hit."
After watching Harvey get out of the inning, Mets manager Terry Collins believes he has a special pitcher on his hands.
"That's the mark of a true ace right there," Collins said. "It's late in the game, you're getting tired -- and he was, he was getting tired -- and he knew he had to get out of that inning. And he reached back for a little extra and made huge pitches. That's why we can't say enough things. This kid's at the beginning of a long, very successful career, and games like tonight can make you expect great seasons."
Washington's bullpen then showed once again that it has become a weakness this year. Reliever Drew Storen pitched the eighth inning, and the Mets played home run derby on the right-hander as Davis and Duda both homered again. It marked sixth time in his career that Davis has had a multihomer game, while Duda has four multihomer games.
Harvey won Round 1 in the pitchers' duel with Strasburg. How did Strasburg feel about the hype leading up to Friday's game?
"It's funny, you guys want to make a big deal out of all this, but every game is huge for me," Strasburg said. "I want to go out there and help this team win. It doesn't matter who is facing us. We are all out there as a collective group to try to get the job done. We weren't able to do that tonight. We have another game tomorrow. Hopefully, Gio [Gonzalez] can go out there and shut the door, get the bats going and win the series."
With the loss, the Nationals dropped their record to 9-7.