PHILADELPHIA — The Phillies' tepid offense couldn't overcome more first-inning struggles for starter Kyle Kendrick.
Jayson Werth homered and drove in four runs, and Tanner Roark pitched seven strong innings to lead the Washington Nationals to a 10-3 victory over Philadelphia on Sunday.
Ryan Zimmerman also went deep and had two RBIs, Ian Desmond knocked in two runs, and Anthony Rendon had three hits and an RBI for Washington
Kendrick entered leading the majors with 21 earned runs in the opening frame. That went up to 24 when the first three batters of the game scored on Werth's three-run homer.
Kendrick retired the next 14 batters, but the damage was already done.
"It was a tough tone set for us early on in the game, and we didn't bounce back from that," Phillies manager Ryne Sandberg said.
Rebounded has been deal for the struggling Philadelphia offense. The Phillies finished a forgettable first half in familiar fashion, producing little offense against Roark and Ross Detwiler.
They scored two unearned runs off Aaron Barrett in the ninth to end with three runs or fewer for the 49th time this season.
The Phillies dropped to 8-41 overall and 2-29 in their last 31 games when failing to score four runs. Cody Asche had two doubles and an RBI for Philadelphia, which fell 10 games behind first-place Washington in the NL East.
"We didn't get anything going on the offensive side of things," Sandberg said.
Kendrick (4-9) continued his pattern of struggling badly in the first inning and then pitching well.
Werth followed consecutive singles by Denard Span and Rendon to lead off the game with an opposite-field shot that quickly made it 3-0.
Kendrick ran into trouble in the sixth when the Nationals scored four runs off him and left-handed reliever Mario Hollands. Kendrick allowed Rendon's single to start the frame and then hit Werth to put runners on first and second before getting Adam LaRoche to fly out.
Zimmerman's one-out sacrifice fly scored Rendon and chased Kendrick. Hollands then surrendered three straight hits, including Desmond's two-run double and Jose Lobaton's RBI single, that broke the game open.
Kendrick left after allowing five runs and five hits with five strikeouts and no walks in 5 2/3 innings. The focus afterward was on his continuous first-inning struggles.
"It's just quality pitches," Kendrick said. "I just have to make pitches in that first inning. That's what it comes down to."
Sandberg said the Phillies have tried to solve Kendrick's opening-inning problem to no avail.
"It's really hard to pinpoint," Sandberg said. "It's been addressed and talked about. He's experimented with some things. He seems to at times get away from his fastball early and go to secondary pitches early on, and those were two pitches that were hit today.
"It's a tough start right off the bat when the first three guys come in."
It was the second straight defeat for Philadelphia after a five-game winning streak in which the Phillies averaged 6.2 runs.
But they had no answers for Roark (8-6), who allowed a run and four hits. He struck out six and walked none.
"I pitched with confidence today," Roark said. "I didn't nibble."
The Phillies got a run back on Ryan Howard's groundout in the bottom of the sixth before scoring a pair in the ninth.
Werth remained hot in July, raising his average this month to .375 (15-for-40) with six homers and 19 RBIs.
LaRoche went 0-for-5 with a strikeout to drop his average in July to .122 (5-for-41). LaRoche was the only Washington starter not to get a hit.
NOTES: Nationals reliever Tyler Clippard was selected to the All-Star game by NL manager Mike Matheny, replacing Braves starter Julio Teheran. Clippard will be the only Washington representative after starter Jordan Zimmermann had to bow out on Saturday because of a right biceps strain. Clippard, who earned the win for the NL in his only other All-Star appearance in 2011, is 6-2 with a 2.03 ERA in 40 innings. ... Desmond, who led major league shortstops in RBIs entering Sunday, increased his total to 57. ... Phillies left-hander Cliff Lee, on the DL since May 19 with an elbow strain, will return to the mound on July 21 against San Francisco. ... Chase Utley will represent the Phillies at the All-Star game, making his sixth appearance. The only NL second basemen to make more All-Star starts than Utley are Hall of Famers Joe Morgan (seven) and Phillies manager Ryne Sandberg (nine).