Baltimore has won five in a row, and at 27-14, the O's are 13 games over .500 for the first time since June 22, 2005, when they were 42-29. The Orioles beat the Nationals, 2-1, in 11 innings on Friday before a 6-5 victory on Saturday.
Chen's first season in the Major Leagues has gone about as well as it could: The left-hander is 4-0 with a 2.45 ERA and hasn't allowed more than three earned runs in any of his seven starts. He beat the Yankees and CC Sabathia in his last start, allowing two runs in seven innings on Tuesday.
"I definitely [felt] really good the last couple of outings," Chen said through an interpreter. "But right now I'm just trying to extend my innings and lower my [pitch] counts."
Standing in the way of Chen's fifth victory and a Baltimore sweep is Nationals ace Stephen Strasburg. Still, Chen relishes the chance to face off against one of the National League's best young arms.
"I heard about him, I heard he's a really good pitcher," Chen said. "Fastball velocity, breaking ball and commands both. I feel like I'm lucky to go against him."
Chen will be making his first start in Interleague Play, but he's used to stepping into the batter's box. In Japan, Chen had to bat in every game he started. But how will he approach the hard-throwing Strasburg?
"I'll just bunt," he said, laughing.
Meanwhile, Strasburg is looking to bounce back from his worst outing of the season. He allowed four runs on seven hits in a season-low four innings against the Padres on Tuesday for his first loss of 2012.
Prior to that loss, Strasburg had gone at least six innings in each of his previous seven outings. He is 3-1 with a 2.25 ERA and 56 strikeouts in 48 innings this year.
The Nationals have lost three in a row and five of their last seven games.
Orioles: Jones streaking
Adam Jones extended his hitting streak to 11 games with a single in the first inning on Friday night. It's the third hit streak of at least 10 games for Jones this season.
Jones went 3-for-4 on Saturday with a two-run home run in the third inning off starter Ross Detwiler. The outfielder has homered in four of his last five games and leads the O's with 14 roundtrippers.
Baltimore has the best road record in the Majors at 15-5.
Nationals: Johnson overhauls lineup
Manager Davey Johnson shook up his lineup for Saturday night's game, trying to find a spark for the Nationals' struggling offense.
Steve Lombardozzi assumed the leadoff sport for Ian Desmond, who fell to fifth in the order.
"I just needed to shake it up," Johnson said. "I felt like the offense is sputtering a little bit. Sometimes when you're sputtering a bit, change clears the air."
Lombardozzi went 2-for-5 with an RBI in Saturday's loss, while Desmond went 1-for-4 with a double.
The Orioles are 12-0 on the road when scoring at least four runs.
The Nationals are 17-21 against the O's since the clubs began playing each other in 2006.
Baltimore is 10-2 in day games.