Arizona's Haren (14-6, 3.12 ERA) and San Diego's Peavy (9-9, 2.84) rank in the league's top 10 in ERA, but they didn't look like elite pitchers Wednesday. Haren allowed five runs, including four in the first inning, and a season-high 11 hits in six innings.

"Obviously, I didn't have good stuff today," he told the Diamondbacks' official Web site.

The Diamondbacks, though, provided him with plenty of run support against Peavy, who gave up a season-high six runs, walking four batters while matching a season-low with two strikeouts in the 8-6 loss.

"It's unacceptable when you can't hold that lead," said Peavy, who has lost three of four starts with a 3.60 ERA in August. "I just didn't have it. I couldn't throw the ball where I wanted to throw it. I just didn't make pitches. That's all there is to it."

Peavy has an ERA under 3.00 for the fourth time in five seasons, and he's one win shy of his sixth straight campaign with at least 10. But he's been mediocre in his career against the Diamondbacks, going 11-11 with a 4.88 ERA in 25 starts, including 1-2 with a 3.32 ERA in 2008.

Haren, who hadn't given up more than three runs in any of his first six career games against the Padres, is 3-1 with a 2.72 ERA against them after Wednesday's meeting. He doesn't expect San Diego to have as much success against him Monday.

"I face them again in five days, and hopefully I'll be able to make the adjustment and go out there and have a better game plan against them," he said.

Haren hopes to help Arizona (68-62) bounce back from a frustrating loss to Florida. The Diamondbacks managed four hits and went 0-for-6 with runners in scoring position in the 5-2 defeat Sunday, but found some consolation in completing a 4-2 homestand and protecting their lead in the division.

"To go 4-2 ... is a good thing," said shortstop Stephen Drew, who was 2-for-4 with a home run and two runs scored Sunday and is batting .358 with 19 runs in his last 22 games.

Peavy gets the ball for a last-place San Diego team that's returning from a winless six-game road trip that included a three-game series against Arizona. Overall, the Padres have dropped seven straight, one shy of their season high set from June 21-29.

San Diego appeared to be on the verge of snapping the skid when it took an early 3-0 lead against San Francisco on Sunday, but the Padres couldn't hold the lead, losing 7-4 to fall a season-high 34 games under .500.

San Diego has lost 10 of 15 meetings with Arizona this season, including four of six at Petco Park.