Peavy will try to get back on track Sunday afternoon with a sixth straight victory against Pittsburgh as the Pirates and Padres play the decisive third game of their series at Petco Park.

Peavy (2-2, 5.13 ERA) got off to a quick start last season, going 3-0 with a 1.20 ERA through four starts.

At the same point in 2009, however, the right-hander hasn't looked nearly as sharp. He gave up three runs in each of his first three starts before submitting his worst outing yet Tuesday at San Francisco, giving up seven hits and six runs over six innings as the Padres (10-7) lost 8-3.

Edgar Renteria's fourth-inning grand slam - the first allowed in 1,284 1-3 career innings by Peavy - served as the game's turning point.

"You just can't make a mistake like that, especially with the pitcher on deck," Peavy told the Padres' official Web site. "It didn't cut and became an 80 mph fastball over the plate. He did exactly what he's supposed to do."

Peavy's career numbers against the Pirates (10-7) suggest he has a good shot at bouncing back on Sunday. He lost his first career start to Pittsburgh in 2003, but is 5-0 with a 1.30 ERA in six games since then, and he's struck out at least nine in each outing.

He fanned 10 while giving up just a run and four hits over seven innings in a 3-1 win at PNC Park on July 27.

The Pirates had the NL's worst ERA last season on their way to 95 losses, but three weeks in this year, they shockingly have the best ERA (2.97) in all of baseball.

Zach Duke gave Pittsburgh's starters their ninth win of the season - they had 33 in 2008 - on Saturday, pitching 8 1-3 innings as the Pirates cruised to a 10-1 victory.

"The way we're playing we feel like we can win every game, regardless whether we're home or away," Duke said.

Ross Ohlendorf (1-2, 3.00) helped lower Pittsburgh's staff ERA with his latest effort, which resulted in his first career win as a starter. He allowed two hits over seven innings while striking out five Monday in an 8-0 victory against Florida.

"Tonight was a very good building block for him," manager John Russell told the team's official Web site. "He's still in a little bit of a development stage. He's going to go through a few growing pains here and there. He's going to continue to make progress."

Ohlendorf has started once against the Padres, giving up five hits and one run but walking four in 4 2-3 innings at Petco on Sept. 28. He didn't earn a decision in Pittsburgh's 6-1 win.

Center fielder Nate McLouth, who leads the Pirates with four homers and 14 RBIs, had a three-run home to support Ohlendorf on Tuesday, but he's missed the first two games in San Diego with a strained right oblique.

Pittsburgh will hope to have McLouth back Sunday, but it won't have shortstop Jack Wilson, who was put on the disabled list late Saturday because of a sprained middle finger.

The Padres, meanwhile, were without their starting shortstop for a scarier reason. Luis Rodriguez was taken to a local hospital after developing an allergic reaction to something he ate, and it's unlikely he'll play Sunday.