While he hasn't been exactly lights out, Barry Zito has been good enough on the mound as of late that the San Francisco Giants have won each of his last seven starts.

Zito hopes to serve as a good luck charm again on Saturday night in the middle portion of a three-game series against the Arizona Diamondbacks.

The left-handed Zito has gone 3-0 with a 4.54 earned run average over his last seven starts since his last loss on Aug. 2. While the Giants have often needed to score runs when the veteran takes the hill, Zito took care of business on his end last time out on Sunday.

Taking on the Dodgers, Zito contributed 6 1/3 innings to a 4-0 triumph, scattering four hits and three walks while improving to 11-8 with a 4.33 ERA in 28 starts this year with the victory.

The 34-year-old wasn't as fortunate the previous start against the Diamondbacks on Sept. 3, when he allowed four runs over five innings to take a no-decision.

Zito is 5-8 in his career versus Arizona with a 5.26 ERA and will be opposed tonight by D'backs rookie Wade Miley, who is coming off a win over the San Diego Padres last Saturday even though he yielded five runs on eight hits and three walks over 5 1/3 innings of an 8-5 triumph.

"The offense did a great job setting the tempo early in the game and they picked me up throughout the night," Miley said.

The 25-year-old lefty, a NL Rookie of the Year candidate, is 15-9 with a 3.07 ERA in 28 games, including 25 starts. One of his early-season relief stints came against the Giants on April 8 and Miley picked up a win with four scoreless frames. This will be his first time facing San Francisco since.

The Giants trimmed their magic number to winning the NL West to 11 with Friday's series-opening 6-2 victory. Hunter Pence capped a five-run third inning with his third career grand slam, while Buster Posey drove in a run and scored twice.

"(Pence) had a great at bat. He did battle back, got a pitch he could handle there and he smoked it," Giants manager Bruce Bochy said. "That's huge, we got one run in and to get a grand slam, that gives you a little cushion, which we needed."

Matt Cain allowed one run on four hits over five-plus innings to pick up the win despite walking a season-high five batters. San Francisco won its third in a row and for the eighth time in 12 games, maintaining a 7 1/2-game edge over the Los Angeles Dodgers in the division.

Chris Johnson went 2-for-3 and drove in both runs for the Diamondbacks, who had won five of seven overall entering the game.

Tyler Skaggs was pegged with the loss after giving up five runs on five hits over four innings.

"(Skaggs) made a mistake to Pence. That is the big one," D'backs manager Kirk Gibson said. "All the other stuff, that happens. He throws a high fastball right where you don't want to throw it. That was their big blow."

Though the Giants are 33-21 against the NL West this season, that includes just a 6-7 mark versus the Diamondbacks.