NEW YORK -- The Washington Nationals didn't need Stephen Strasburg to subdue the stumbling New York Mets.
John Lannan filled in for what was initially scheduled to be Strasburg's final start with 5 2/3 scoreless innings Wednesday night, and four relievers finished off a 2-0 win for Washington.
Ryan Zimmerman and Ian Desmond homered for the Nationals, who swept the three-game series at Citi Field. The win moved Washington 8 1/2 games ahead of the Atlanta Braves, and took a little edge off the weekend series in Atlanta.
The homer extended Zimmerman's hitting streak to 16 games, and he also reached base twice on walks.
The reeling Mets were swept for the second straight series at home and were shut out for the second time on the home stand. They have managed just nine runs in those six games.
Matt Harvey (3-5) again showed promise, striking out 10 batters, but got the latest hard-luck loss for the Mets. He allowed just one run on five hits in five innings.
With Strasburg done for the season with the Nationals' much-debated plan to protect his surgically repaired right arm, Lannan got the nod. Washington had originally planned for this to be Strasburg's last start, but decided the extra attention was causing a distraction to him and told him after his last start he was done for the year.
Lannan had started at least 25 games in the past four seasons, but was demoted in spring training and pitched for Washington in just one game in July and August.
"Lannan was good, very focused," Nationals manager Davey Johson said of the Long Beach, Long Island, native. "With the experience he had up here, I knew he'd do well."
The Mets have been humbled in the second half, especially after a surprising start when they were contending early in the season. Especially humbling is the fact that two NL East rivals now have more wins at Citi Field since the All-Star break than they do. The Nationals have won six games there, the Braves five, and the Mets only four.
"It's frustrating for all 35 guys in that clubhouse, besides the players, and the coaches and the front office," Mets manager Terry Collins said. "To not play well at home, to not score runs. ... Our club wasn't picked to be very good and we set the bar up there and I'm proud of that, proud we could do that, and I think it's great that there are expectations and we expect to play that way, and right now we just cannot seem to recreate what happened in April."
The glimpse of excitement these days for the Mets is watching Harvey pitch, and Collins was again impressed with how well he started out, though both he and the rookie starter said he needs to pitch to contact more so he can go deeper into games.
But Collins pointed out that Wally Backman, who managed Harvey at Class AAA Buffalo and joined Collins' staff after the minor-league season, was surprised at what he saw.
"When Wally says, 'I never saw that. I never saw that kind of stuff,' it shows you how he can raise his game," Collins said. "... I tell you, he's been so impressive, you know we've got something special. We've got something very special, and it's been very, very fun to be around him to watch him work and watch him get ready."
Robert Carson did an impressive escape job to keep Harvey from allowing more runs, entering with the bases loaded in the sixth and retiring the next three batters without allowing a run.
Lannan (3-0) pitched well in his first turn in Strasburg's spot, as he allowed five hits while walking one and striking out two.
"I have to go out there and do what I do," Lannan said of taking over for Strasburg. "I can't compare myself to him, because what he's done is unbelievable."
Sean Burnett, who hadn't pitched since Sept. 2 due to nerve irritation in his left elbow, put two runners on in the ninth. But, with closer Tyler Clippard having thrown 19 pitches the previous night and having pitched four of the last five games, Drew Storen came on to get the final out.
Burnett allowed Lucas Duda's second single of the night to start the inning and a two-out single to Andres Torres. But Storen retired pinch hitter Daniel Murphy on a fly ball to end the game.
The Nationals escaped their own bases-loaded jam in the sixth, when reliever Christian Garcia entered with two on and two outs, then hit Kelly Shoppach with a pitch. But Garcia got pinch hitter Ike Davis to fly out to center to end the threat.
New York again wiggled out of a bases-loaded jam in the seventh. Reliever Justin Hampson got Adam LaRoche to ground into an inning-ending double play. But Desmond hit his 23rd homer of the season, off of Jon Rauch, to start the eighth and give Washington a 2-0 lead.
The Mets lost second baseman Ronny Cedeno in the sixth, as he left with tightness in his right hamstring and was replaced by Jordany Valdespin.
The Nationals took a 1-0 lead on Zimmerman's home run to center to start the fourth.
It was the only blip early against Harvey, who struck out the first four batters.
NOTES: Duda started at first base Wednesday instead of his usual left field, as Collins said he will find more ways to get him in the lineup down the stretch so he can evaluate him for next season. ... Murphy was scratched from Wednesday's starting lineup due to a sore lower back, but entered the game as a pinch hitter. ... The Mets re-signed with Class A Savannah and the city will remain affiliated with the organization through 2014, the Mets announced. ... Nationals slumping left fielder Michael Morse was out of the lineup Wednesday with a bruised bone and torn sheath in his left wrist, Johnson said in his pre-game press briefing. The injuries were revealed by an MRI, while X-rays were negative. He will take batting practice before Friday's game at Atlanta and be evaluated again at that point.