They've been pretty consistent over the past several seasons against Roy Oswalt, but that isn't something they're proud of.Seeking his first victory in nearly seven weeks, Oswalt looks to continue his dominance over the Dodgers when he takes the ball for the Philadelphia Phillies on Tuesday night at Citizens Bank Park.Los Angeles (28-33) had little luck in Monday's series opener against Cliff Lee, who struck out 10 in seven shutout innings. The Dodgers finally scored off reliever Ryan Madson in the ninth but still ended up losing 3-1.Monday's offensive dud came after Los Angeles combined for 20 runs in winning its previous two games against Cincinnati.This has been an ongoing problem for the Dodgers, who have scored 46 runs while batting .329 in their last six victories but have scored four times and hit .191 in their last five losses.Matt Kemp is in the middle of this erratic stretch, driving in 13 runs in the wins and two in the defeats."We've got to find a way to break though," manager Don Mattingly said.That might not be so easy against Oswalt (3-3, 2.70 ERA).The right-hander won each of the two starts he made against the Dodgers last season with the Phillies, yielding six hits over 13 1/3 scoreless innings. In six starts versus Los Angeles since 2007, the three-time All-Star is 5-0 with a 1.49 ERA. He has a 0.74 ERA in those victories.Kemp is hitless in eight career at-bats against Oswalt, striking out four times, while Andre Ethier is batting .176 lifetime against him.Oswalt has a 1.96 ERA in four starts since coming off the disabled list with a sore lower back, but has been backed by three total runs of support leaving him with an 0-2 record. Oswalt, who has yielded two runs or fewer in eight of his nine starts, hasn't won since April 21, against San Diego.At Washington on Wednesday, Oswalt gave up two runs and six hits in five innings of a 2-1 loss.Philadelphia's offense hasn't only struggled in Oswalt's starts.The Phillies (36-24), who were without leadoff hitter Jimmy Rollins (bruised right knee) for a second straight game Monday, were limited to six hits in the opener, and have plated three runs or fewer in five of six games.Shane Victorino, who took Rollins' place at the top of the batting order Monday, is 3 for 16 (.188) in four games since coming off the DL with a strained right hamstring."I feel like it's going to come around," manager Charlie Manuel said. "I'm waiting though."Philadelphia hopes to have better luck against Rubby De La Rosa (1-0, 1.80), who is making his first major league start.De La Rosa was called up from Double-A Chattanooga on May 24, and has yielded a run and three hits in five innings over three relief appearances. The right-hander, who went 2-2 with a 2.93 ERA in eight starts in the minors, is taking the spot in the rotation of Jon Garland (right shoulder inflammation).