They'll try to extend their winning streak at San Francisco to eight games for the first time in over 11 years Saturday night when the clubs continue their three-game series.The Pirates (60-80) have won 16 of the last 19 meetings with the Giants (60-80), including all four matchups this season. They've also taken seven games in a row at San Francisco, outscoring the Giants 45-17 while posting a .305 batting average and a 2.14 ERA.Pittsburgh last won eight consecutive road games against the Giants from June 10, 1996-April 1, 1997, for its longest road winning streak in the all-time series.The Pirates continued their current run Friday, beating San Francisco 7-0 behind a six-hitter from Zach Duke."We get tired of being beat up by anybody," Giants reliever Jack Taschner said.Friday's game also had a light earthquake rattle the San Francisco Bay area around 9 p.m. local time, and registered as a preliminary 4.0-magnitude by the U.S. Geological Survey. During the 1989 World Series here between the Giants and Oakland Athletics, a 6.9 earthquake hit during warmups before Game 3 and delayed the conclusion of the Series.The Pirates will give the ball to Paul Maholm (8-8, 3.81 ERA), who is looking to rebound from one of his worst performances of the season.The left-hander was tagged for six runs and seven hits, including two homers, in 5 1-3 innings of an 11-3 loss to Milwaukee last Saturday. It was his shortest outing since lasting five innings in a loss at Washington on May 3, and came after he went 1-0 with a 1.93 ERA in his four previous outings."He's done a phenomenal job all year and you've got to figure that at some point he's going to hit a bump in the road because everyone does," Pirates manager John Russell said.Maholm is 1-0 with a 3.43 ERA in three starts against San Francisco, with Pittsburgh winning all of them.The Giants, losers of six of their last seven, hope Matt Cain (8-11, 3.69) can avoid losing a third consecutive start.The right-hander is 0-2 with a 6.55 ERA and nine walks in 11 innings over his last two starts. He struggled with his control again Sunday, getting reached for five runs and eight hits while walking a season high-tying five and hitting another batter in five innings of a 9-3 loss at Cincinnati."Walks have killed us all year," Giants manager Bruce Bochy said. "Enough's enough. You have to pound the strike zone."Cain is 0-2 with a 5.71 ERA in three starts against Pittsburgh.