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Rookie left-hander Jeff Locke aims to end a season-worst five-start winless stretch on Thursday when the Pittsburgh Pirates open a four-game set with the San Francisco Giants at AT&T Park.

Locke was a huge reason behind the Pirates' first half success, but the 25- year-old hurler has just one win since the All-Star break and was roughed up badly by Arizona his last time out. Locke lasted just 2 2/3 innings of that one and allowed eight runs and 10 hits, dropping him to 9-4 on the year, while ballooning his ERA to 2.90.

"He was short on stuff and command," Pittsburgh manager Clint Hurdle said. "That's a tough combination."

Locke has been good on the road this season, though, and is 5-2 with a 1.81 ERA in 12 starts away from home.

Pittsburgh will need Locke at his best tonight, as it tries to rebound from a 2-1 loss in San Diego on Wednesday.

Gerrit Cole (6-6) was the hard-luck loser for giving up two runs on 10 hits and five strikeouts over six innings for the Pirates, who have dropped eight of 12 and saw their lead in the NL Central fall to just one game over St. Louis.

"I just felt like I let a good opportunity slip away," said Cole. "We had a chance coming in here to take a sweep and I feel like I let the team down."

San Francisco, meanwhile, has lost three of four after getting hammered by the Boston Red Sox, 12-1, on Wednesday.

Making his first start since July 30, Barry Zito (4-9) lasted just 3 2/3 innings and was roughed up for six runs on seven hits.

Hoping for a better effort on Thursday, the Giants will turn to righty Matt Cain, who is 8-8 with a 4.35 ERA. Cain snapped a personal two-game losing streak on Saturday in Miami, as he held the Marlins to a pair of runs and four hits in seven innings.

"I felt good," Cain said afterward. "(Catcher Buster Posey) and I kind of got things going early. We were throwing strikes and letting the defense work."

Cain tossed 6 2/3 scoreless innings to beat the Pirates earlier in the year and is 3-2 lifetime against them with a 2.79 ERA in 10 starts.

Pittsburgh, which took two of three from the Giants earlier in the year, has 9,799 wins since joining the National League in 1887. With another victory, it'll join the Giants, Cubs, Braves, Dodgers and Yankees as the only Major League clubs to amass 9,800 all-time wins.