Baltimore made sure its offense didn't slow down despite beginning the Battle of the Beltways in Washington.
The Orioles look to cap a six-game road trip with another victory on Tuesday night when they finish up the first half of four straight meetings with the Nationals.
This annual series between the clubs will resume with games in Baltimore, starting on Wednesday.
The Orioles came out on top 6-2 in Monday's opener, marking their 10th straight road game of scoring at least five runs. That broke the previous franchise record of nine set from July 19-Aug. 8, 1998.
Baltimore went ahead for good with a three-run fourth inning, which featured a big two-run single by Nick Markakis. He extended his hitting streak to 12 straight games and is hitting .377 over that time with 11 RBI.
"I got my pitch, didn't miss it, and found grass in the outfield," Markakis said of his base hit. "It ended up being big and we got a lot of big hits out of a lot of guys. It was a team effort and a great team win."
Yamaico Navarro also drove in two runs, while Chris Davis and Matt Wieters had an RBI each as Baltimore won for the fifth time in seven games.
Jason Hammel outdueled Washington's Gio Gonzalez with eight innings of two-run ball. He also struck out eight to improve to 6-0 lifetime versus the Nationals.
Gonzalez, meanwhile, lasted 5 2/3 innings and was charged with four runs on eight hits.
"He just didn't go after them when he needed to," Nationals manager Davey Johnson said of Gonzalez. "He left a lot of pitches up."
Ryan Zimmerman and Tyler Moore drove in the lone Nationals' runs as the club lost for the sixth time in its last nine games and was without outfielder Bryce Harper.
Harper, who is also expected to sit out tonight's game, suffered a left knee injury when he collided with the outfield wall at Dodger Stadium on May 13. He aggravated the injury in Sunday's win over Philadelphia and the Nats are resting their young outfielder so as to not risk further damage to the knee.
Harper, though, joins Jayson Werth and second baseman Danny Espinosa as regulars sidelined by injury.
Washington's hobbled lineup will face off against Baltimore right-hander Kevin Gausman, who makes the second start of his major league career.
The fourth overall pick of the 2012 draft out of LSU, Gausman made his debut on Thursday and kept his team in a loss against Toronto. He allowed four runs on seven hits and two walks over five innings, striking out five in suffering defeat.
The 22-year-old featured a high-90s fastball and a very good change-up that left his manager impressed.
"I like the way he presented himself," O's skipper Buck Showalter said on his team's website. "You could see his presence. I'm proud of him."
Gausman, who went 2-4 with a 3.11 earned run average in eight starts with Double-A Bowie this season, will be countered by another young hurler in Nate Karns, who makes his MLB debut.
A 2009 draft pick out of Texas Tech, Karns will fill in for the injured Ross Detwiler, who is on the disabled list due to a right oblique strain. The right-hander was named the Nats' Minor League Pitcher of the Year last season and is ranked their sixth-best prospect according to MLB.com.
The 25-year-old is 4-2 with a 4.60 ERA in nine starts with Double-A Harrisburg this season.
Baltimore took four of six games from the Nats last season.