In what has been a pitcher's series so far, the Washington Nationals and the Baltimore Orioles will duke it out this afternoon in the rubber game of the Beltway Series at Camden Yards.

The Nationals claimed Saturday's game, 3-1, thanks to an all-around great pitching performance from their staff.

Edwin Jackson (4-4) was stellar as usual, allowing just one run and four hits in 6 1/3 innings, while adding five strikeouts to just one walk. In the process, he lowered his season ERA to 2.91.

Jackson's performance was especially impressive considering he didn't feel he had his best stuff during warmups.

"It was just one of those days you don't have blow-away stuff," Jackson said. "You just have to go out and pitch. That's pretty much what it was from the time I started throwing in the pen, I knew what kind of day it was going to be."

Three relievers combined to allow just one hit and no runs in 2 2/3 innings for Washington, with Tyler Clippard pitching a perfect ninth for his 12th save.

Adam LaRoche belted his 13th home run of the season for the Nationals, while Michael Morse added two hits as the designated hitter.

For the Orioles, Wei-Yin Chen (7-3) allowed three runs (two earned) in five innings of work.

Baltimore's only run came courtesy of Adam Jones's 19th home run of the year.

The Nationals will send Ross Detwiler to the hill this afternoon, as he returns to the starting rotation to replace the struggling Chien-Ming Wang.

Detwiler was effective as a starter early in the season, going 2-1 with a 1.64 ERA in April, though struggles in May relegated him to a bullpen role.

The southpaw settled into his middle relief role, allowing just two earned runs in his last six appearances (13 1/3 innings). He pitched 3 2/3 innings of perfect baseball in his last outing on June 19 against the Rays.

Detwiler was roughed up by the Orioles on May 19, earning the loss by allowing nine hits and six earned runs in five innings of work.

Jake Arrieta will toe the rubber for the Orioles. The right-hander has been wildly inconsistent this season, ranging from brilliant (7 IP, 1 ER, 9 K in a June 13 win over Pittsburgh) to horrible (4 IP, 11 H, 9 ER in a June 8 loss to Philadelphia).

In all, the bad performances have outweighed the good, as he is just 3-9 with a 5.83 ERA on the season.

He's faced the Nationals three times in his career, going 0-1 with a 7.20 ERA.