Barry Zito tries to claim his first victory in over three months as he gets the call for the San Francisco Giants on Monday afternoon for the opener of a three-game set against the San Diego Padres.

Zito has lost seven straight decisions and is winless in 16 consecutive appearances since a victory over Oakland on May 30. The struggling left-hander pitched out of the bullpen to begin August, then finished the month by making a pair of starts.

He lost both, giving up 11 runs, 16 hits and three walks over a combined 7 2/3 innings. Zito is 4-10 with a 5.81 earned run average in 27 games (23 starts) this season.

"There's some bad luck in there. He just left some pitches up too, though," Giants manager Bruce Bochy said after Zito allowed five runs in four innings of Monday's 6-1 loss to the Colorado Rockies.

The 35-year-old Zito has pitched well versus the Padres this year, going 1-1 with a 3.44 ERA in four starts.

The Giants are coming off a series victory, taking two of three over the Arizona Diamondbacks. They won Sunday's finale 8-2 behind an excellent outing from Yusmeiro Petit.

Petit struck out 10 over seven-plus innings, giving up two runs on seven hits and a walk. It was his second straight victory after he picked up a win at Colorado on Tuesday.

"That's another great start for him in two tough ballparks," said Bochy. "He had great command, hit his spots and mixed it up. He's got some savvy out there. He knows what he's doing."

Hunter Pence homered and had three hits, while Buster Posey also had three hits and drove in two runs.

The victory moved Giants out of last place in the NL West, one game ahead of the Padres. San Diego was swept in three games over the weekend by the Los Angeles Dodgers and has lost five of its last six.

Tyson Ross fanned a career-high 10 batters and gave up just one run over five innings, but Dale Thayer gave up a homer to the Dodgers' Yasiel Puig in the sixth and the Padres went on to lose 2-1 for a second straight night.

"Our pitchers are giving us a chance to win. We're just one big hit away," Padres manager Bud Black said.

Chase Headley was out of the Padres' starting lineup for a fourth straight game because of a sore lower back.

San Diego will start Ian Kennedy, who turned in his worst outing since being acquired from Arizona prior to the non-waiver trade deadline. That start came against his former Diamondbacks club as he yielded six runs on six hits and five walks over 4 1/3 innings. Kennedy did not get a decision and is 2-1 with a 4.55 ERA in five starts with the Padres.

"It was difficult; I knew it would be a little different," Kennedy told his club's website of facing his former team. "I just put myself in holes, putting guys on; I walked a lot of guys. It's tough to do that. But it (was) a lot tougher than I thought it would be."

The 28-year-old righty is 5-9 with a 5.10 ERA in 26 starts this season and will face the Giants for the fourth time in 2013. In the previous three meetings, all with Arizona, he went 0-1 with a 3.32 ERA.

The Giants have won five of their last six meetings with the Padres and lead the season series 8-5.