Zito again will try for his first National League win as the Giants (3-7) meet the Pittsburgh Pirates in the opening game of a doubleheader on Sunday.
The left-hander was to start Saturday's contest, which was rained out, and poor weather could postpone these games as well. Sunday's forecast calls for rain and snow showers and temperatures in the 40s.
Zito went 102-63 with a 3.55 ERA pitching with Oakland from 2000-06 and was highly sought in free agency before signing a seven-year deal and the richest contract ever for a pitcher on Jan. 2.
In his first two NL starts, though, Zito (0-2, 8.18 ERA) has struggled and is coming off one of the worst outings of his career. He lasted six innings in the Giants' 10-4 loss to the Los Angeles Dodgers last Sunday, but was tagged for eight runs and nine hits as opponents increased their batting average against him to .295. San Francisco, meanwhile, is hitting just .239 when Zito pitches.
"You've got to focus on doing your job and keeping the team in the game," Zito told the Giants' official Web site. "If you start to take on the burdens of the offense ... it's not going to go as planned."
But Zito could be in line for a win if Barry Bonds continues to hit well against the team he broke into the major leagues with more than two decades ago. The seven-time NL MVP was 3-for-3 with two homers -- leaving him 18 shy of tying Hank Aaron's all-time record -- as the Giants won 8-5 on Friday night.
Bonds was hitting just .192 with one homer coming into this series before singling home Omar Vizquel during a five-run first inning. He then hit a two-run homer in the second off starter Zach Duke and added a solo shot in the fourth off Shawn Chacon to make it 8-2 before being lifted.
Bonds has hit 96 of his 737 homers in Pittsburgh, but just seven in PNC Park since it opened in 2001.
"We've been trying to get this offense going and that's what we needed," said Giants manager Bruce Bochy.
With 70 career multihomer games, Bonds also is two behind Babe Ruth's major league record of 72.
Ian Snell (0-1, 2.08) is the scheduled starter for the Pirates in the opener. The right-hander gave up one run and six hits over seven innings Tuesday against reigning World Series champion St. Louis, but Pittsburgh lost 3-0 in its home opener.
He was dominant in his only career start against the Giants, holding them to three hits with three walks and five strikeouts through seven innings of a 2-0 road win on June 10. Snell, who leads the Pirates with 14 strikeouts in 2007, has never faced the Giants at home.
San Francisco's Matt Cain (0-1, 2.77), who gets the ball in the second game, was the hard-luck loser in Monday's 1-0 defeat to San Diego. He tossed six no-hit innings before San Diego's Khalil Greene doubled to lead off the seventh.
"I didn't think much of it until someone yelled something in the fifth or the sixth," Cain said of the no-hit bid. "That was not a big deal. I was worried about keeping guys off base."
The right-hander didn't get a decision in his only career start at Pittsburgh last year.
Tony Armas (0-1, 13.50) will make his home debut for the Pirates in the second game. He made his first start with Pittsburgh on April 7 after spending 1999-2006 with the Montreal-Washington franchise, and gave up six runs, eight hits and walked five over four innings of a 7-5 loss at Cincinnati.
While with the Nationals, Armas lost his only start versus the Giants in 2006, when he yielded six runs and eight hits in 3 2-3 innings of an 8-6 defeat on Aug. 2 in San Francisco. Overall, the right-hander is 1-4 with a 5.28 ERA in five starts against the Giants.