Since manager Davey Johnson decided to flip-flop his batting order, the surging Washington Nationals appear to have found their groove at the plate.
After his team was limited to a total of one run and 13 hits in consecutive losses July 2 and 3, Johnson moved shortstop Ian Desmond up to second in the batting order and dropped outfielder Jayson Werth down to sixth.
Since then, Washington (46-42) is averaging 8.0 runs with a .341 batting average while winning four straight games. Werth has gone 8 for 13 with five runs and Desmond has also scored five times while going 6 for 15.
Ryan Zimmerman provided the big blow with a grand slam and Bryce Harper added three hits in Sunday's 11-7 win over San Diego to cap a 5-2 homestand.
"We've played below our potential and now we're coming around,'' Johnson said. "That's a good feeling.''
The Nationals, four games behind NL East-leading Atlanta, will try to extend their longest win streak since a five-game run from May 4-10 in the opener of a seven-game road trip.
Haren (4-9, 6.15 ERA) is scheduled to come off the disabled list to start in place of Ross Detwiler, who was placed on the DL on Sunday with lower back trouble.
Haren, who was sidelined with a shoulder injury, is 0-6 with a 7.01 ERA while giving up 11 home runs in eight starts since beating Detroit on May 9.
The right-hander hasn't fared well against the Phillies (43-46) in two matchups this season, yielding seven runs and 11 hits - three homers - over 12 innings. Haren did not get a decision either time, but the Nationals lost both contests.
Ryan Howard, Domonic Brown and Erik Kratz have homered off Haren in 2013, though he won't have to face Howard after the slugger was placed on the DL on Saturday because of a left knee injury. The team revealed Monday that Howard needs surgery to repair a torn meniscus, and he'll miss at least six to eight weeks.
Brown helped the Phillies fill the void with his 23rd homer and a triple in Sunday's 5-1 win over Atlanta. The outfielder is 8 for 21 with two homers and four RBIs in his last five games.
"We have to go right now,'' said Brown, who is 4 for 31 with one homer in 12 career home games against the Nationals. "We're definitely fighting and battling.
"Hopefully we can win the series against the Nats."
The Phillies give the ball to left-hander John Lannan (1-3, 5.15) as they return home looking for their fifth win in seven games.
Lannan has been inconsistent, going 1-2 with a 4.50 ERA in four starts since missing two months with a strained quad. He allowed four runs, a season-worst 11 hits and three walks over five innings in a 6-5 loss at Pittsburgh on Wednesday.
The former National pitched much better in his only career start against Washington on June 17, giving up two runs and six hits over five innings before leaving without a decision in a 5-4 win.
Werth appears to have a good chance to continue his surge since he's 9 for 27 with four homers all-time in this matchup.
Desmond, though, is 3 for 28 with 11 strikeouts in his last eight games in Philadelphia.
The teams have split the six meetings this season, with the Phillies taking two of three at home last month.