Zito held the Reds to five hits in his ninth quality start of the season, but his six walks proved costly, especially in the fourth inning. With Brandon Phillips on first, Zito walked three straight Reds batters to give Cincinnati the lead.
"It was a good effort," manager Bruce Bochy said. "He got off a couple innings there and battled himself. He threw six innings and gave up one run; that's a great job. Unfortunately, we ran into another well-pitched game."
On the heels of Mike Leake's one-run complete game in Friday's 5-1 Reds win, Latos kept the Giants off balance while pounding the strike zone. He finished with seven strikeouts and no walks.
Brandon Crawford's third-inning double was the Giants' only hit until pinch-hitter Brandon Belt tripled in the ninth and scored on Gregor Blanco's groundout.
"It's been a rough two nights," Blanco said. "[Latos] did a great job today commanding his sliders and off-speed pitches. He used to be an aggressive pitcher, throw a lot of fastballs and try to dominate with the fastball, but today he was different. He was using his slider and curveball, and that made it difficult."
Latos has been especially tough on the Giants and now has a 2.18 career ERA against them in 11 appearances, including a 1.67 ERA at AT&T Park. On May 13, 2010, the then-Padres starter was a Eli Whiteside sixth-inning infield single away from a perfect game.
In his last outing, Latos threw a one-run complete game in the Reds' 3-1 win against the Brewers.
"He's tough, and he has great stuff," Bochy said. "We knew we had our work cut out, and he has been tough on us. We knew what we were going into. When a good pitcher is on top of his game, you just do all you can to compete and get some runs, and we just had a tough time today."
The Reds got a needed insurance run in the seventh when Miguel Cairo's RBI single off reliever George Kontos plated Zack Cozart.
"A team is a team," Latos said, dismissing his career success against the Giants. "No matter who I am facing, it's good to get a win."
Zito reported a tweak in his neck while warming up for the game and Bochy said he thought it may have affected his pitching, although the veteran left-hander downplayed the role of his stiff neck in the outing.
"It just kind of affects you until your adrenaline comes and takes over," Zito said. "And then you just battle through it. That kind of stuff happens a lot."
The Giants' offense was subdued despite entering the game averaging 5.44 runs of support for Zito, the highest among Giants starters. Zito has not earned a win against the Reds since Aug. 8, 2009.
Brad Penny pitched 2 1/3 perfect innings in relief, making his 2012 debut after getting called up from Triple-A Fresno on Friday. He struck out Ryan Ludwick after he came on in the seventh with runners on first and third with two outs.
"He really pitched well," Bochy said. "He kept the game where it was and got out of a jam. That's what you're hoping for -- to keep it close. Unfortunately we just couldn't do anything offensively. We got shut down again."