The World Series champions continue their road trip with a short trek north to Miller Park, where they open a three-game series Tuesday night against the Milwaukee Brewers.
Often maligned for underperforming after signing his seven-year, $126 million contract in 2007, Zito (2-0, 0.00 ERA) was a key contributor to the Giants (9-4) winning their second title in three years in 2012.
The left-hander finished third on the team with 15 wins, went 2-0 with a 1.69 ERA in three postseason starts and triggered San Francisco's sweep of Detroit in last year's Fall Classic by outpitching Justin Verlander in Game 1.
Zito's good vibes have carried over with consecutive seven-inning scoreless outings to open 2013 and extend his winning streak to 11, including the postseason. He scattered seven hits and walked one Wednesday when the Giants rolled to a 10-0 victory over Colorado.
"You can't have more confidence out there than what Barry has right now," manager Bruce Bochy said. "It's fun to watch when a pitcher's on and hitting his spots. It's a thing of beauty. He's as tough a competitor as I've ever been around."
Despite his long run of success, Zito appears to measure it on a start-by-start basis.
"It's hard to speak about a stretch or a run or the past, really," said Zito, who hasn't lost since Aug. 2. "Today the boys came out swinging. They were starting to click on all cylinders offensively, which was great because a lot of people underestimate our offense. And days like today really show what we can offer."
Zito, who is 6-0 with a 3.44 ERA in his past 10 road starts, was roughed up in Milwaukee for eight runs - four earned - in three innings of an 8-5 defeat May 23. It's his only appearance versus the Brewers since the start of the 2011 season.
The Giants have won Zito's last 16 starts, a streak last accomplished by the team behind Carl Hubbell from July 17-Sept. 30, 1936.
San Francisco took three of four from the Chicago Cubs at Wrigley Field, capped with Sunday's 10-7, 10-inning victory as the Giants took advantage of repeated miscues by Cubs pitchers that included five wild pitches in one inning. Hector Sanchez scored the go-ahead run on a balk before Buster Posey and Marco Scutaro added RBI hits.
Milwaukee (3-8) may be hard-pressed to continue its momentum against Zito after barely avoiding a sweep at St. Louis over the weekend. Ryan Braun ended the Brewers' club-record 32-inning scoreless streak with a two-run homer in the seventh and Jonathan Lucroy hit a solo shot in the 10th for a 4-3 win that ended a three-game losing streak.
"It's been a scuffle," manager Ron Roenicke said. "It's been really difficult to get wins thus far. We did a nice job battling back in the eighth and the ninth. That's always a positive."
Braun has had plenty of positives against Zito, going 5 for 14 with three homers, a double and a triple.
Wily Peralta (0-1, 4.50) pitched better in his second start of the season than his first and left without a decision at Wrigley Field last Tuesday after giving up three runs and six hits in 6 2-3 innings of a 6-3 loss.
The right-hander, making his first appearance against San Francisco, is 1-1 with a 2.33 ERA in three career home starts.