Updated

The Washington Nationals hope that Dan Haren can get on track Friday evening when they try to secure a series victory over the rival Philadelphia Phillies in the second of three straight encounters.

Haren has lost back-to-back starts since winning three in a row and was drilled for a season-high seven earned runs over five innings of a 13-4 loss at San Diego on Sunday. The righty also yielded nine hits and a pair of walks in falling to 4-5 with a 5.54 earned run average in nine outings this season.

"I made a bunch of mistakes in the first inning. I was able to keep it close for a while. You can't keep letting balls over the plate to a professional lineup like that," Haren said on the Nats' website. "I was fighting myself out there with mechanics. I was working behind in the count too much. That's a recipe for disaster."

The 32-year-old takes aim at his first career victory versus the Phillies, having gone 0-3 with a 6.14 ERA in four previous meetings.

The consistent Jonathan Pettibone draws the seventh start of his career tonight for the Phillies.

The 22-year-old righty has yet to allow more than three runs in any of his six starts, producing a 3-0 record with a 3.00 ERA. The Phillies are 5-1 in his appearances.

Pettibone did not get a decision in his club's 3-2 win over the Cincinnati Reds on Sunday. He allowed two runs -- one earned -- on seven hits and three walks over a career-best seven innings.

Pettibone will face the Nationals for the first time and has a 5.06 ERA in two road starts.

He'll try to draw the Phillies even in this series after the Nationals won Friday's opener 5-2 behind a four-run fifth inning. Steve Lombardozzi capped the frame with a two-run double, one of his three hits in the game.

Adam LaRoche added an RBI triple in the rally, with Kurt Suzuki knocking in the other run in the decisive fifth frame. That allowed Washington to win its second straight following a four-game slide and the club sits two games ahead of third-place Philadelphia. The Nats are four games behind the NL East- leading Atlanta Braves.

Jordan Zimmermann limited the Phillies to two runs on six hits over seven strong innings to win his eighth game of the campaign, while Rafael Soriano retired the visitors in order in the ninth to nail down his 14th save of the season.

"It felt really good to get (Zimmermann) some runs. Early on we've been scoring early then shutting down. To get on the board and pour on four more late was nice. It's a real nice cushion, especially with him on the mound," LaRoche said.

Domonic Brown went 2-for-3 with an RBI and a run scored, while Erik Kratz plated the other run for the Phillies, who had won seven of 10 coming into the contest.

Kyle Kendrick was charged with all five runs on eight hits and four walks over five innings to absorb the loss.

"He was having problems throughout the night. He had a big pitch count in the first two innings. He was having trouble," Phillies manager Charlie Manuel said of his starter.

The Phillies and Nationals split 18 meetings a season ago, but Washington has won five of the last six in this series.