SAN FRANCISCO (AP) -- Nate Schierholtz's recent power surge might not be enough to turn the Chicago Cubs season around. It sure is making the year a lot easier for the slugging outfielder to handle.
Getting a game-winning home run against his former club? Well, that's just icing on the cake.
Cheered in every at-bat this series by the crowd at AT&T Park, Schierholtz homered off ex-teammate Sergio Romo with one out in the ninth inning to lift the Cubs to a 1-0 win over the San Francisco Giants on Saturday night.
"I can't really describe it, but it felt good," Schierholtz said. "I always loved playing here. I love the fans here. I couldn't ask for a better reception."
Dropped to sixth in the Cubs' lineup after batting cleanup a night earlier in the club's first game after trading Alfonso Soriano, Schierholtz worked a full count off Romo (3-6) before hitting a towering blast into the right field stands to hand Romo his second loss in as many games.
Schierholtz played with San Francisco from 2007-2012 before getting traded to Philadelphia in exchange for Hunter Pence midway through last season. He signed with Chicago as a free agent in the offseason and had been bothered by shoulder problems earlier in the year before heating up over the past two weeks.
The home run off Romo was Schierholtz's 14th of the season and third on the team's current 10-game road trip. Seven of his 10 hits on the road trip have been for extra bases.
"It's pretty nice to watch," Cubs manager Dale Sveum said. "It's obviously huge for him to do that to his old team."
Starlin Castro added two hits for Chicago, which is 18-13 in its last 31 games.
Madison Bumgarner pitched eight shutout innings for San Francisco but left without a decision. The World Series champs have lost six of seven and are a season-high 11 games under .500.
Since May 13, the Giants have the worst record in the majors at 23-42.
"We're in a tough rut now and we know it," San Francisco manager Bruce Bochy said. "We just have to keep working and trying. We couldn't even get a cheap hit and we got what we deserve."
Pedro Strop (1-0) pitched one inning for the win despite making two mental mistakes that helped the Giants load the bases with no outs in the eighth. Strop twice made late throws on sacrifice bunt attempts but got out of it when Buster Posey and Pablo Sandoval grounded into forceouts at home and Hunter Pence struck out.
"That was one of our more exciting innings of the year," Sveum said. "We were going to win it or lose it there."
Kevin Gregg worked the ninth for his 21st save to complete the five-hitter, getting pinch-hitter Tony Abreu to ground into a 3-2-3 double play after San Francisco loaded the bases with one out.
The Cubs won their second straight in this three-game set after dropping three of four to the Giants at Wrigley Field in April. Chicago scored two unearned runs in the ninth inning to beat San Francisco 3-2 on Friday.
This one went down to the wire again.
Chicago only got one runner to second base until Schierholtz's homer.
That was enough to hold off the slumping Giants, who were shut out for the ninth time this season.
Both starters were dominant but left without a decision.
Chicago rookie Chris Rusin needed just 27 pitches to get through the third inning and didn't allow a baserunner until Pence's one-out walk in the fifth. One batter later Joaquin Arias grounded a single to center to end the no-hit bid.
Rusin also worked out of a two-on, two-out jam in the sixth and got help in the seventh when first baseman Anthony Rizzo made a leaping stab of Brandon Belt's high liner to strand Pence at third base after he led off the inning with a ground-rule double.
Bumgarner was equally effective until leaving for a pinch hitter in the eighth.
The Giants' most consistent starter this season and an All-Star, Bumgarner overcame a pair of errors behind him and pitched out of a two-on, two-out jam when Andres Torres made a diving catch on Schierholtz's sinking liner in the sixth. He finished with seven strikeouts and two walks.
NOTES: The Giants committed two more errors and lead the majors with 76 this season. ... Giants RHP Ryan Vogelsong threw 45 pitches over 2 2-3 innings in his second rehabilitation outing after going on the disabled list with a fractured right hand. Vogelsong will accompany the big league club on a trip to the White House on Monday before joining Double-A Richmond for his next appearance. ... RHP Tim Lincecum (5-10, 4.73 ERA), who allowed eight runs on Monday in his first start since throwing a no-hitter, pitches for the Giants in the series finale. ... LHP Travis Wood (6-7, 2.95) goes for Chicago and is winless in four career starts against San Francisco. ... Giants pitching coach Dave Righetti rejoined the club after having elbow surgery Wednesday.
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