How it happened: Nate Schierholtz delivered the game-winning blast with his towering home run to right field off Giants closer Sergio Romo in the top of the ninth. But it was standout pitching that put Chicago in a position to win its second straight over the reigning World Series champs. Cubs relievers escaped bases-loaded jams in the eighth and ninth, with Pedro Strop escaping a no-out situation in the eighth and Kevin Gregg coaxing Tony Abreu into a game-ending home-to-first double play in the ninth. That ending overshadowed a terrific start from left-hander Chris Rusin, who blanked San Francisco over a career-high seven innings. He surrendered only three hits and two walks to go along with three strikeouts. It was by far Rusin's best effort as a big leaguer. He didn't allow his first baserunner until issuing Hunter Pence a one-out walk in the fifth. He finished his night by escaping a runner on third, one-out jam in the seventh. First he retired Joaquin Arias on a weak groundout to third, then first baseman Anthony Rizzo made a leaping stab of Brandon Belt's liner to end the threat.
What it means: The Cubs have had their roster stripped by trades in the past month and they may deal more players before Wednesday's non-waiver trade deadline, but they continue to play spirited baseball despite harboring no hopes for the postseason. Chicago (47-55) is 18-13 over its past 31 games.
Outside the box: Schierholtz stretched his career-high homer total to 14. ... Strop's Houdini act in the eighth continues an impressive start to his Cubs career. Since coming over in a July 2 trade from Baltimore, the right-hander has deliverd 11 scoreless appearances, with 12 strikeouts in 9 2/3 innings.
Up next: Left-hander Travis Wood (6-7, 2.95) takes the ball for Chicago in the finale of a three-game series at AT&T Park. Wood is just 2-4 over his past 10 outings but has delivered quality starts in eight of those. The Giants counter with Tim Lincecum (5-10, 4.73), who got shelled for eight earned runs against Cincinnati on Monday in his first start since throwing a no-hitter. First pitch is 3:05 p.m. CT.