In Strasburg's slot, Lannan leads Nats over Mets

"It's definitely strange. There's a lot of strange things going on," Lannan said. "What's going on with Stras, it just hasn't happened before."

Ryan Zimmerman homered in the fourth off rookie Matt Harvey (3-5) and Ian Desmond connected off Jon Rauch in the eighth, helping the NL East leaders complete a three-game sweep and open an 8½-game lead over the second-place Braves heading into a three-game series at Atlanta starting Friday. The Nationals are closing in on the capital's first postseason baseball berth since the original Washington Senators in 1933.

"This was a big series," manager Davey Johnson said. "We need to kind of drive the nail in their coffin over here and come into Atlanta in a good frame of mind."

A native of nearby Long Beach, Lannan (3-0) struck out two and walked one in an 81-pitch outing. Lannan, Washington's opening-day starter in 2009 and 2010, was 9-11 with a 4.30 ERA at Triple-A Syracuse and asked the Nationals to trade him when he was demoted at the end of spring training.

"It all happened for a reason, I guess," he said. "I just don't look back on it with anger or anything. It just is what it is. It happened, and we've just got to move on."

Pitching before about 20 family members and friends, he made his first appearance since a minor league outing on Aug. 30 and improved to 4-1 with a 1.69 ERA in his last six starts against the Mets. Without Strasburg's dominant fastball, the left-handed Lannan relies on changing speeds and control.

"He earned a lot of respect in this clubhouse," said reliever Sean Burnett, who gave up two hits and got two outs in the ninth — his first appearance since Sept. 2 following a layoff caused by an irritated nerve in his pitching elbow.

Drew Storen came in and retired pinch-hitter Daniel Murphy on a game-ending flyout with runners at the corners for his second save. The surging Nationals have won nine of 11 and 12 of 15.

Harvey struck out 10 in five-plus innings, his latest impressive performance. New York, however, finished an 0-6 homestand and dropped to 65-78, falling 13 games under .500 for the first time since finishing 2009 at 70-92. The Mets have lost eight of nine overall.