San Francisco Giants manager Bruce Bochy said he has plenty of confidence in Ryan Vogelsong, but he may find it tough to put his trust in the struggling righty come playoff time given the hurler's current troubles.

Vogelsong will try to begin a round out to form on Sunday when the Giants take aim at a three-game sweep of the Arizona Diamondbacks.

The 35-year-old Vogelsong has struggled to a 2-3 mark over his last six starts with a 9.57 earned run average, yielding 28 runs over 26 1/3 innings. He does have 32 strikeouts in that span, but fanned only one in a 6-5 loss to the Colorado Rockies on Monday while giving up four runs on six hits over five frames.

Vogelsong remained a win shy of matching his total from last year's breakout season as he dipped to 12-8 with a 3.40 earned run average through 27 outings this season.

"He's one of our guys, he's going to be out there," Bochy said. "We have all the confidence in the world in him."

Vogelsong lasted just 3 1/3 frames against the Diamondbacks on Sept. 4, giving up six runs without getting a decision. He is 2-2 lifetime against them with a 3.28 ERA in 12 games (6 starts).

Arizona rookie Patrick Corbin is going through some similar struggles that he would like to end with today's start as well. He is 0-3 in his past four outings, getting touched for 14 runs in 21 frames.

The 23-year-old southpaw got a no-decision against the Giants on Sept. 3, then suffered an 8-2 loss to the San Diego Padres on Sunday. He was charged with three runs on six hits and two walks in 5 1/3 frames.

Corbin is 5-7 with a 4.19 ERA in 18 games this season (13 starts) and did beat the Giants the first time he faced them back on May 11.

San Francisco enters this finale with a 7 1/2-game lead over the Los Angeles Dodgers for first place in the NL West after taking last night's encounter with the Diamondbacks 3-2.

Buster Posey hit a two-run homer and finished a triple shy of the cycle, while Marco Scutaro had a pair of hits and drove in a run to help the Giants win their fourth straight.

Barry Zito struck out four over 6 2/3 frames, giving up just one run on six hits and a walk to earn his fourth straight winning decision.

Angel Pagan hit his 13th triple of the season, passing Willie Mays (1960) and Steve Finley (2006) for the most in a single season by a Giants hitter since the franchise moved to San Francisco in 1958.

Wade Miley pitched well despite the loss, allowing all three runs on eight hits over seven frames. Justin Upton clubbed a solo shot for the D-backs, who had won five of seven prior to this series.

"We didn't have many (chances)," Arizona manager Kirk Gibson said. "A couple of chances with runners in scoring position in which we scored only four run in two nights."

Though the Giants are 34-21 against the NL West this season, that includes just a 7-7 mark versus the Diamondbacks.