When the ninth inning arrived, in came Casilla, who sported a 6.75 spring ERA. He preserved San Francisco's lead with relative ease by working a perfect ninth inning. The right-hander ended the game by fanning Arizona slugger Paul Goldschmidt on a 3-2 slider.
"His rhythm was good the whole inning," catcher Buster Posey said of Casilla, who finished with a career-best 1.70 ERA last year.
Asked whether he worried about the bullpen's performance after his seven-inning stint ended, Giants starter Madison Bumgarner politely swatted away the question.
"I've got confidence in the guys out there," Bumgarner said. "It doesn't matter if you win by six or win by one, as long as you get the game in the win column."
Chris Haft is a reporter for MLB.com. Read his blog, Haft-Baked Ideas, and follow him on Twitter at @sfgiantsbeat. This story was not subject to the approval of Major League Baseball or its clubs.