The outcome, which unfolded after rain delayed the first pitch for one hour and 11 minutes, kept the Giants atop the NL West standings. They lead San Diego by a half-game and Colorado by 2 1/2 games.
Upon gaining admission to the Giants' cramped clubhouse at Wrigley Field, reporters were treated to the rare sight of almost no player making a move to shower or dress. Virtually every Giant was monitoring telecasts of San Diego's 6-0 victory at Los Angeles and Colorado's 3-1 loss at Arizona.
The Giants seem to sense that the competition will only thicken.
"It's almost like you want to go ahead and skip to the last two or three games," Posey said. "You figure it's going to come down to the last two or three games."
Instead of fast-forwarding to their fate, the Giants have opted to enjoy themselves thoroughly. Their six-year absence from the postseason is the longest among NL West clubs, so they're relishing the journey to October, which is new for many of them.
"This is something we've kind of been a part of, but not really to this extent," said Cain, referring to last season's push for the Wild Card, which ebbed in mid-September. "We're obviously wanting to go out there and do our business. As long as we take care of our business, good things will happen. We're playing like every game counts, which it does."
Posey doubly strengthens the Giants' bid. The 23-year-old catcher helped Cain assert himself at the outset by throwing out Starlin Castro, another of the NL's many glittering rookies, on a first-inning stolen-base attempt. From Cain's airtight six-inning effort to the three perfect innings that Ramon Ramirez (1-0), Sergio Romo and Brian Wilson (44th save) contributed, Posey remained a steadying presence.
"To catch a shutout, that's probably as big a thrill as anything," Posey said. "Cain was really, really, really, really good. He probably could have pitched eight innings, at least. But that just goes to show how good our bullpen is."
Cain sustained his second-half excellence by allowing just two singles, including an infield hit. Matching Cubs starter Carlos Zambrano, who also threw six shutout innings, Cain permitted one runner to reach second base as he trimmed his ERA to 2.50 in 13 starts since the All-Star break. But with Cain due to lead off the seventh inning, manager Bruce Bochy removed the right-hander for pinch-hitter Travis Ishikawa (who grounded out) in the endless and fruitless quest for offense.
"Anybody can be a better hitter than I am to lead off the inning," Cain said good-naturedly.
Posey provided the only scoring with one out in the eighth by lofting a 3-1 fastball from Andrew Cashner (2-6) toward center field and into the basket lining the top of the outfield wall.
Though Posey believed that he connected solidly with Cashner's 95-mph heater, his 15th homer traveled barely out of reach, which might have been a result of the inclement weather.
"I thought I got it," Posey said. "The way the ball was traveling in [batting practice], I thought I got it for sure. But I guess after the rain came, the air was a little bit thicker."
Cashner, who said he faced Posey in Arizona Fall League and Spring Training competition, felt no shame.
"I tried to go away and the ball ran back in. It was still a good pitch," Cashner said. "... If I'm going to get beat, I'm going to get beat on my best stuff and he beat me."
Similarly, Posey's best might not be enough to earn him Rookie of the Year honors. The crowded field also includes Atlanta outfielder Jason Heyward, Florida's Mike Stanton and Gaby Sanchez, St. Louis left-hander Jaime Garcia and a host of others. Conventional wisdom suggests that Heyward, who unlike Posey opened the season in the Majors, is the favorite to capture the award.
Bochy diplomatically said that he hasn't given much thought to Posey's chances in the Rookie of the Year race. But he spared nothing as he evaluated Posey's impact upon the Giants.
"It's hard to have a better game than that," Bochy said after the Giants' fourth 1-0 decision in their last 10 games. "He's the guy you want up there with the game on the line and behind the plate. I've just been so impressed with the growth of this kid."