LOS ANGELES -- After defeating their archrivals in the first two games of this series, the Giants may have been due to return to earth. That they did, quite literally.

They eroded Dodger Stadium's earth by hitting into 16 groundouts against Los Angeles' Chad Billingsley, who pitched his second career shutout in a 2-0 decision Wednesday night.

"I didn't see this coming, the way we've been swinging the bats," Giants manager Bruce Bochy said.

Losing this one hardly constitutes a letdown for the Giants, who have won 11 of 14 games while capturing four series in a row. But San Diego's 12-inning triumph over Atlanta restored the Padres' four-game lead in the National League West, which should remind the second-place Giants that setbacks such as this one must be kept to a minimum.

The Giants should be able to avoid prolonged slumps if they continue to receive the quality of pitching Barry Zito provided. The left-hander allowed six hits and both of Los Angeles' runs in 7 1/3 innings, sustaining the momentum he established on Friday, when he permitted the Mets two hits in eight innings.

Zito's primary lapse occurred in the second inning, when he threw what he described as a "flat slider" that Casey Blake lofted down the left-field line for a home run. Zito proceeded to subdue the Dodgers until the eighth inning, when he yielded Rafael Furcal's leadoff single and walked Andre Ethier with one out. In came Sergio Romo, who surrendered Blake's RBI single.

"He kept us off-balance pretty good," Blake said of Zito. Referring to his homer, Blake said that he "just happened to catch one on the barrel and something good happened. Fortunately that was enough for us."

The suggestion that repeating such efforts will generate more victories than defeats didn't console Zito (8-5), who bellowed briefly but angrily as he stalked back to the dugout after being removed.

"I'm not content," Zito said. "I'm frustrated giving up that bomb to Blake and frustrated with the walk to Ethier. Those are things I need to get better at."

The Giants still need to get better at hitting in the clutch, despite entering the game as the NL's highest-scoring team in July. They went 0-for-8 with runners in scoring position against Billingsley (8-5), who recorded Los Angeles' first complete game of the season.

Dodgers second baseman Ronnie Belliard inhaled Freddy Sanchez's sharp third-inning grounder up the middle and shoveled the ball from his glove to shortstop Furcal for a forceout at second base, ending a two-on, two-out threat.

Aubrey Huff doubled to open the fourth inning for San Francisco's first hit and moved to third on Buster Posey's groundout to second base, but Billingsley responded by retiring Pablo Sandoval and Juan Uribe on two more grounders.

Bochy noted that the Dodgers' infield played back on Sandoval until the count reached two strikes. At that point, the infielders moved halfway across the dirt. Had Sandoval put the ball in play earlier in the count, Huff likely would have scored.

The Giants wasted Nate Schierholtz's one-out double in the fifth inning, as well as singles by Sanchez and Posey in the sixth. The latter extended Posey's hitting streak to 15 games, but San Francisco's scoreless streak continued as Sandoval flied out and Uribe grounded out.

Sanchez collected a one-out infield hit in the eighth before center fielder Matt Kemp ran down line drives by Huff and Posey.

Billingsley gave the Giants no chances in the ninth, as he continued to throw his fastball at 96 mph. Travis Ishikawa, who grounded out to end the game, was suitably impressed.

"For me, he had a fastball, cutter, and good command of his curveball," said Ishikawa, who went 0-for-4 after beginning the game 6-for-12 in his career off Billingsley. "He's got good stuff, so he can still make a mistake and you can just miss it."