Washington has lost four straight games and dropped its record to 38-65.
Lannan had a 1-0 lead after five innings, but one had a feeling he had to be perfect the rest of the way because the Nationals have the worst offense in baseball and are not capable of scoring a lot of runs, especially off a tough right-hander like Chad Billingsley, who pitched 7 1/3 innings and gave up two runs.
Indeed, Lannan wasn't perfect. He suddenly lost it in the sixth inning and found himself overthrowing. Lannan should have put the leadoff hitter, Juan Pierre, away. Pierre was behind, 0-2, but worked the count to 2-2, when he singled up the middle.
"I had him the whole game pretty much. I was throwing good pitches to him," Lannan said. "That breaking ball was up. That was a big at-bat."
After Matt Kemp took the first pitch and singled to left field, Lannan hit Russell Martin with an 1-2 pitch to load the bases.
Two batters later, Nomar Garciaparra singled to left-center field to drive in Pierre and Kemp.
Martin then scored on a groundout by James Loney.
"I tried to do too much. I went away from what I was doing all game," Lannan said. "I just tried to, I guess, overthrow, especially when I had the bases loaded. [Pitching coach] Randy [St. Claire] came out and settled me down. I'm just glad I came out in the seventh inning and got my composure back and had a quick inning."
Lannan pitched seven innings and gave up the three runs on five hits. It was also his 15th quality start. Unfortunately, he has a 6-10 record to show for it. The good thing is, Lannan never has shown any emotions in public about having a losing record or not getting enough run support.
"Every start, I look at the positive and negatives and take something from it," Lannan said. "I don't look at the outcome that much. I just try to learn and take whatever I can in. I definitely learned a lot today. You can't be perfect in this game. I don't know how many perfect games they are in the history of baseball. There's not many.
"So no one is perfect. Everyone has his struggles. You have to battle through them. I have to go out there and do my job. I really don't go out there and look at records. I just try to go out there and do what I can."
Washington made it a 3-2 game in the eighth inning and had a chance to do more damage. However, the team didn't get the job done with the bats.
With two outs and a runner on second, Ryan Zimmerman blooped a single off Billingsley to score Ryan Langerhans. After Austin Kearns singled to put runners on first and second, Dodgers manager Joe Torre brought in right-hander Jonathan Broxton to face Jesus Flores, who struck out on four pitches.
"I knew it was going to be tough for me because that guy throws hard," Flores said. "I tried to look for a good pitch. He threw good pitches and put me away. I can't say too much about him."
In the eighth, Joel Hanrahan pitched a scoreless inning. It was his first game since manager Manny Acta named him the closer on Tuesday. Hanrahan, who was drafted by the Dodgers, needed the work and Acta wasn't going to wait for a save situation to put him in the game. Hanrahan struck out two batters.
"I tried to go out there and keep the game close and give us a chance. We just came up a little short," Hanrahan said. "It was fun facing the Dodgers. It wasn't like I was out there to get him. It's fun facing some of the guys you know. Usually, I haven't had much success against people that I know."
Bill Ladson is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.