SAN FRANCISCO – St. Louis was unable to capitalize on opportunities with runners on base Tuesday night as the Cardinals fell to the Giants 5-0 in the first game of a three-game set at San Francisco’s AT&T Park.

Over the first five innings, the Cardinals left six runners on the bases, including the bases being loaded in the fourth. Of those runners, three were left in scoring position.

The Cardinals best opportunity came in the top of the fourth. St. Louis (44-40) loaded the bases with no outs, but was unable to get a run across the plate.

Jhonny Peralta doubled and moved to third on Matt Adams single. Yadier Molina was then hit by a pitch to load the bases, but that’s when everything fell apart. Allen Craig and Jon Jay both struck out before Daniel Descalso grounded out to second to end the inning.

“That was a great opportunity we had,” Cardinals’ skipper Mike Matheny said. “We just couldn’t do anything with it.”

In the bottom of the fourth, the Giants struck hard and fast to take the lead. Hunter Pence singled and Buster Posey followed with a double down the left field line that just landed fair. Pence scored from first on the play. The next batter, Pablo Sandoval, launched his 100th career home run into the left field bleachers, giving the Giants a 3-0 lead.

“You know, whether people believe in momentum or not,” Matheny said, “but it is usually not a coincidence that right after that, they come up with the big inning and get something going.”

Like his previous start, the opposition got to Cardinals’ rookie starting pitcher Gonzales the second time through the lineup.

“The first time through the lineup I was able to throw all my pitches for strikes and get ahead of hitters,” Gonzales said. “The second time through, I just started leaving some things up. … I just wasn’t able to capitalize the second time through.”

The Giants (47-36) increased their lead over the Cardinals with two more runs in the fifth.

Gonzales failed to get out of the fifth inning. Gonzales was charged with five runs on seven hits and four walks, one of which was intentional. Gonzales struck out just two batters.

“He is better than what his line has shown the last two (performances),” Matheny said. “Today he made more mistakes in the top of the zone and they didn’t let him get away with much.”

Even with taking his first loss, Gonzales saw improvement.

“Tonight I saw improvement in my curveball and I was able to throw it for strikes,” Gonzales said. “It was a little better than it was in Denver, so I was happy with that. And my cutter is coming along.”

Seth Maness relieved Gonzales (0-1) and pitched 1.2 innings before giving way to Jason Motte for the seventh. Motte set the Giants down in order, marking the first perfect inning by a Cardinals pitcher since the first inning.

The Cardinals mustered just five hits all night while the Giants finished with eight. Matt Carpenter extended his hitting streak to six games with a fifth inning single. Carpenter also reached via a walk. Adams’ single in the fourth extended his hitting streak to a career-high eight games.

These two teams will be back at it tonight when Adam Wainwright faces off against Ryan Vogelsong. First pitch is slated for 9:15 p.m.

NOTES: In the bottom of the sixth, Tim Lincecum walked but wasn’t paying attention to the count. The home plate umpire had to hold up four fingers to the Giants’ pitcher before he realized and trotted down to first base.