Lannan was cruising until the fifth inning. After walking Nick Hundley, who advanced to second base on Chris Young'ssacrifice bunt, Will Venable hit a grounder to second baseman Emilio Bonifacio, who committed an error, allowing Hundley to score. Edgar Gonzalez followed with a two-run homer. None of the three runs were earned.
Two innings later, Young hit his first big league home run. Lannan lasted seven innings and gave up four runs, but only one was earned.
"Lannan was outstanding," manager Manny Acta said. "He made one mistake and that was the leadoff walk, which in the baseball dictionary means trouble is coming. That attracted the error and the home run. Lannan had great command of his fastball and just cruised, pretty much."
In the top of the eighth inning, the Nationals played sloppy baseball with Charlie Manning on the mound. Brian Giles led off and hit a routine line drive right at left fielder Willie Harris, but Harris lost the ball in the lights and the ball went over his head for a triple. Adrian Gonzalez then singled home Giles.
Harris has had problems with the lights all season, but Saturday was a forgettable experience. An inning earlier, Venable hit a ball to Harris, who didn't see the ball until it approached him. He was able to get a glove on it, but it dropped in for a double. In the second, Harris lost Chase Headley's liner in the lights, but made the catch at the last moment, ending up flat on his back.
"I have to deal with the lights, and the other team has to deal with them," Harris said. "But we haven't been hitting many balls in the lights. [The other teams] have been hitting the balls in the lights. The ball that I caught off Chase Headley [in the second inning], I wish I could have [seen] it. I had no chance. I didn't see it. You have an idea of where the ball is going to be, and you try to battle and you try to stick with it. Sometimes you get it; sometimes you don't."
After Adrian Gonzalez's single, Kevin Kouzmanoff hit what looked to be a double-play ball to third baseman Ryan Zimmerman, but Zimmerman threw the ball past Bonifacio at second base to put runners on first and third.
"We talked to Zim about that play," Acta said. "We [were] down by five runs. He could have taken a little more time and just gotten an out. He understands that."
Headley followed, singling to left field to bring home Gonzalez.
The Nationals had no chance against Young, who gave up just two hits in seven innings, both singles. Zimmerman said that Young did a great job hiding his fastball and keeping his breaking pitches out of the strike zone.
"He didn't make any mistakes," Zimmerman said. "Any kind of pitcher who does that is tough."
Said Young about his outing: "Early on, I was fighting myself, mechanically. I wasn't as sharp as I would like to be. As the game progressed, I tried to do less. I was trying to make a perfect pitch, throwing hard. So I took a little off and found my rhythm and tempo.
After Young left the game, the Nationals put a run on the scoreboard in the eighth when Bonifacio scored on Aaron Boone's ground-rule double to left field.
The Nationals are in the midst of a four-game losing streak and sit just three defeats away from 100 losses.
"We just play one game at a time," Zimmerman said. "We don't think about anything long-term. We just try to win every game. There's no problem with motivation. I think we play hard every night."
Bill Ladson is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.