However, things started to go wrong for Washington starting in the third inning. After Adam Jones singled to right field, Alex Cintron hit the ball into the gap in left-center field. Milledge tried to make a sliding stop on the play, but it went past him.
As he tried to retrieve the ball, he injured his right groin. Jones was able to score easily, while Cintron ended up with a triple. Milledge would leave the game after the play and was placed on the 15-day disabled list during the seventh inning. Milledge is expected to be out two to four weeks, and the Nationals recalled center fielder Roger Bernadina from Double-A Harrisburg.
"I'm in a little bit of pain right now. I don't know how long it's gong to be. I can tell you this: I'm going to rehab hard and try to get back," Milledge said. "I'm a little bummed out."
Milledge becomes the eighth player from the Nationals' 2008 Opening Day lineup to go on the disabled list. Only shortstop Cristian Guzman has been able to stay healthy this season.
"The kid was leading our team in RBIs. He was making so much progress in center field. He was looking so good and looking comfortable," manager Manny Acta said of Milledge. "He was hitting third and doing everything for us. It's tough. We'll just give another kid a chance.
"The injuries are something you can't control. It could be worse. I just feel bad for Milledge because he was playing very, very well for us."
Two outs later, Nick Markakis hit a routine ground ball to Lannan. The ball hit off his glove and went to second base for an error. It allowed Cintron to score and give the Orioles a 2-1 lead.
A lack of defense came back to bite Lannan again. The next hitter, Melvin Mora, hit the ball toward Lannan's right, but Lannan couldn't come up with the ball, putting runners on first and second. Aubrey Huff then added to the lead with an RBI single.
"Lannan basically hurt himself a lot by not being able to field his position," Acta said. "It's amazing how much Greg Maddux, Jim Kaat and the Tom Glavines of the world have done by playing defense. Lannan was a kid that was in [Class] A ball last year. He needs some more work there."
Defense wasn't the only thing that hurt Lannan.
"I felt good the first two innings. I just kind of lost it. It wasn't there today and you have to move on. It's just a bad outing," Lannan said. "It was not a good one today. They came out hacking. They worked on my fastball. I didn't have my slider or anything else to keep them off balance."
The Orioles would score a combined six runs in the next three innings off Lannan and reliever Jesus Colome. The biggest blows came from Luke Scott and Ramon Hernandez, who hit home runs in the fourth and fifth innings, repectively.
Orioles starter Garrett Olson held the Nationals in check for five innings, allowing one run on six hits. He struck out five batters and walked three.
"We couldn't get anything offensively. He had a good slider. He back doored most of our right-handed hitters. He did a good job," Acta said of Olson.