Cubs manager Dale Sveum moved regular leadoff man David DeJesus down to the No. 3 hole and he delivered with a monster home run.
Now, Sveum needs more from the rest of his lineup.
Matt Cain pitched into the ninth inning and outdueled Matt Garza on the way to winning his fifth straight start, leading the San Francisco Giants past Chicago 2-1 on Saturday.
DeJesus hit a deep solo home run to right-center with two outs in the fourth to put the Cubs on the board. After "hours and hours of deliberating," Sveum dropped DeJesus to third for the first time this year in an effort to spark the struggling Cubs.
"Once again we just couldn't muster up anything against the starter," Sveum said. "It's the same old thing. It's unbelievable how we have a tough time scoring against starting pitchers."
The Giants had to manufacture their runs against Garza.
Aubrey Huff drew a bases-loaded walk to tie the game at 1 in the sixth, then San Francisco went ahead on an RBI fielder's choice by Joaquin Arias on which Huff broke up a would-be double play. Huff produced his first RBI since April 16 and just his fifth this season after he spent a stint on the disabled list with anxiety disorder and is no longer a regular.
"That at-bat was huge," manager Bruce Bochy said. "We got a run in. That's what it takes to win ballgames."
DeJesus' drive wasn't enough to help the Cubs avoid their ninth straight road loss. It is Chicago's longest skid away from Wrigley Field since also dropping nine in a row from Aug. 25 to Sept. 10, 2006.
Cain (6-2) was his dominant self on turn-back-the-clock to 1912 day, playing in the New York Giants' white uniforms with dark blue pinstripes. The Cubs wore head-to-toe navy blue and the scoreboard was black-and-white sans video in the spirit of the Polo Grounds.
"I liked it, it was fun. It was actually one of the most comfortable throwback jerseys we've ever worn," Cain said. "A lot of them are heavy and uncomfortable. It was nice to throw in, it wasn't a big deal."
Cain allowed a leadoff walk to Starlin Castro in the ninth before Bochy turned to Javier Lopez, who induced DeJesus' double play before Sergio Romo recorded the final out for his first save in his first chance. Cain struck out seven and waved after walking off to a standing ovation after an impressive 117-pitch day. He moved his career record to 75-75, the right-hander's first time at .500 since he was 17-17 in 2007.
"Oh, I had no idea," Cain said. "It kind of stinks to have to think, 'to get back to .500,' but that's the way it goes."
He stayed strong in the late innings, getting through a 1-2-3 seventh on seven pitches to put him at 94. He wanted to finish it, and nearly did.
"He had everything working today," Chicago catcher Steve Clevenger said.
Melky Cabrera singled in the sixth for his majors-leading 81st hit for San Francisco, which began the day four games back of the first-place Dodgers for their closest spot to division-leading Los Angeles since May 8. The Dodgers won 6-2 at Colorado earlier Saturday.
DeJesus' second homer of the year was the 16th by an opponent this year at pitcher-friendly AT&T Park compared to just six by the Giants, who still won for the 10th time in their last 14 home games. The clout also snapped an 18-inning scoreless stretch by Cain against the Cubs.
Garza (2-4) struck out six and walked one in six innings, allowing two runs on five hits but lost his third straight start. The right-hander is winless in his last five outings since beating the Phillies on the road April 29.
"I pitched exactly according to the plan. I was throwing the ball downhill and got a lot of groundballs," he said. "I think they hit the ball hard once or twice. I attacked and I pitched my game."
Tony Campana had two hits batting leadoff for the Cubs, who had a three-game winning streak snapped in Friday night's 4-3 defeat. The run came on the heels of a 12-game losing streak.
Angel Pagan singled in the sixth and matched a franchise record with a 26-game home hitting streak. Fitting he did so in a retro uniform, as he tied Mike Donlin's mark set from Aug. 28, 1905, to May 5, 1906.
NOTES: Cain's first career complete game came vs. the Cubs on Sept. 9, 2005. ... Neither team actually played on June 2, 1912. ... Cubs 3B Ian Stewart sat out with a sore left wrist before pinch-hitting in the eighth. Sveum said he was unlikely to start him before Monday's game at Milwaukee. ... 1B Huff to former 1B J.T. Snow: "Did they take BP in 1912?" Snow: "Yeah, and they also took infield." ... The game drew a sellout crowd of 41,239 — roughly 7,000 more fans than the Polo Grounds held in 1912. ... LHP Barry Zito (4-2) pitches Sunday for San Francisco against Travis Wood (0-1).