In the Washington Nationals stacked rotation, Edwin Jackson is often a forgotten man, but he has pitched much better than his 3-4 record would indicate.

Jackson has an ERA of 3.02, which is on pace to be his lowest in six years as a starter. He's often been dominant, as hitters are batting just .213 against him, eighth-best in the National League.

The right-hander has allowed two earned runs or fewer in four consecutive starts. He was the hard-luck loser on June 17 against the Yankees, going six innings while allowing seven hits and two runs.

Jackson has had success against the Orioles in his career, going 5-1 with a 3.25 ERA in 10 games, though he has a 5.16 ERA in 22 2/3 innings at Camden Yards.

For the Orioles, Wei-Yin Chen will attempt to win his fourth straight game for the first time in his major league career.

The Taiwanese lefty is coming off arguably his best performance as an Oriole on June 17, earning the win over the Braves by tossing seven scoreless innings.

Chen's seven wins is tops on the team, and his 3.36 ERA is second to only Jason Hammel's 2.87 among Oriole starters.

In Friday's series opener, the Orioles came out on top, 2-1, behind another masterful performance from Jason Hammel.

Hammel (8-2) followed up a shutout on June 16 with an eight- inning gem, allowing five hits and no earned runs while striking out 10. In the process, he lowered his season ERA to 2.61.

"His outings the last two times out, and really most of the year, have been fun to watch," Orioles manager Buck Showalter said. "When you have command of that many pitches in your repertoire and you put him and (catcher Matt) Wieters on the same team, you like your chances. He was outstanding."

Baltimore got out to an early 1-0 lead after a Mark Reynolds home run in the bottom of the second, his sixth of the year.

The Nationals tied the game up 1-1 with a Roger Bernadina RBI groundout in the top of the fifth, only for the Orioles to respond in the bottom of the inning with a J.J. Hardy RBI double, which proved to be the game winner.

Jim Johnson pitched a scoreless ninth inning for his 21st save.

Jordan Zimmermann (3-6) pitched well in defeat, allowing two earned runs and eight hits over seven innings of work.

The win for the Orioles snapped a three-game losing streak, and they are just 1 1/2-games behind the Yankees for first place in the AL East.